We are able to as a substitute write unit checks that use CSS selectors to probe the
presence and proper content material of particular HTML components inside a doc.
Parameterizing these checks makes it simple so as to add new checks and to obviously
point out what particulars every take a look at is verifying. This method works with any
language that has entry to an HTML parsing library that helps CSS
selectors; examples are offered in Go and Java.
Stage 1: checking for sound HTML
The primary factor we wish to verify is that the HTML we produce is
principally sound. I do not imply to verify that HTML is legitimate in line with the
W3C; it might be cool to do it, however it’s higher to begin with a lot less complicated and sooner checks.
As an illustration, we would like our checks to
break if the template generates one thing like
<div>foo</p>
Let’s have a look at methods to do it in levels: we begin with the next take a look at that
tries to compile the template. In Go we use the usual html/template bundle.
Go
func Test_wellFormedHtml(t *testing.T) { templ := template.Should(template.ParseFiles("index.tmpl")) _ = templ } In Java, we use jmustache
as a result of it is quite simple to make use of; Freemarker or
Velocity are different frequent selections.
Java
@Take a look at void indexIsSoundHtml() { var template = Mustache.compiler().compile( new InputStreamReader( getClass().getResourceAsStream("/index.tmpl"))); } If we run this take a look at, it is going to fail, as a result of the index.tmpl file does
not exist. So we create it, with the above damaged HTML. Now the take a look at ought to cross.
Then we create a mannequin for the template to make use of. The applying manages a todo-list, and
we are able to create a minimal mannequin for demonstration functions.
Go
func Test_wellFormedHtml(t *testing.T) { templ := template.Should(template.ParseFiles("index.tmpl")) mannequin := todo.NewList() _ = templ _ = mannequin } Java
@Take a look at void indexIsSoundHtml() { var template = Mustache.compiler().compile( new InputStreamReader( getClass().getResourceAsStream("/index.tmpl"))); var mannequin = new TodoList(); } Now we render the template, saving the leads to a bytes buffer (Go) or as a String (Java).
Go
func Test_wellFormedHtml(t *testing.T) { templ := template.Should(template.ParseFiles("index.tmpl")) mannequin := todo.NewList() var buf bytes.Buffer err := templ.Execute(&buf, mannequin) if err != nil { panic(err) } } Java
@Take a look at void indexIsSoundHtml() { var template = Mustache.compiler().compile( new InputStreamReader( getClass().getResourceAsStream("/index.tmpl"))); var mannequin = new TodoList(); var html = template.execute(mannequin); } At this level, we wish to parse the HTML and we anticipate to see an
error, as a result of in our damaged HTML there’s a div factor that
is closed by a p factor. There’s an HTML parser within the Go
normal library, however it’s too lenient: if we run it on our damaged HTML, we do not get an
error. Fortunately, the Go normal library additionally has an XML parser that may be
configured to parse HTML (due to this Stack Overflow reply)
Go
func Test_wellFormedHtml(t *testing.T) { templ := template.Should(template.ParseFiles("index.tmpl")) mannequin := todo.NewList() // render the template right into a buffer var buf bytes.Buffer err := templ.Execute(&buf, mannequin) if err != nil { panic(err) } // verify that the template may be parsed as (lenient) XML decoder := xml.NewDecoder(bytes.NewReader(buf.Bytes())) decoder.Strict = false decoder.AutoClose = xml.HTMLAutoClose decoder.Entity = xml.HTMLEntity for { _, err := decoder.Token() swap err { case io.EOF: return // We're completed, it is legitimate! case nil: // do nothing default: t.Fatalf("Error parsing html: %s", err) } } } supply
This code configures the HTML parser to have the precise degree of leniency
for HTML, after which parses the HTML token by token. Certainly, we see the error
message we needed:
--- FAIL: Test_wellFormedHtml (0.00s) index_template_test.go:61: Error parsing html: XML syntax error on line 4: surprising finish factor </p>
In Java, a flexible library to make use of is jsoup:
Java
@Take a look at void indexIsSoundHtml() { var template = Mustache.compiler().compile( new InputStreamReader( getClass().getResourceAsStream("/index.tmpl"))); var mannequin = new TodoList(); var html = template.execute(mannequin); var parser = Parser.htmlParser().setTrackErrors(10); Jsoup.parse(html, "", parser); assertThat(parser.getErrors()).isEmpty(); } supply
And we see it fail:
java.lang.AssertionError: Anticipating empty however was:<[<1:13>: Unexpected EndTag token [</p>] when in state [InBody],
Success! Now if we copy over the contents of the TodoMVC
template to our index.tmpl file, the take a look at passes.
The take a look at, nonetheless, is simply too verbose: we extract two helper capabilities, in
order to make the intention of the take a look at clearer, and we get
Go
func Test_wellFormedHtml(t *testing.T) { mannequin := todo.NewList() buf := renderTemplate("index.tmpl", mannequin) assertWellFormedHtml(t, buf) } supply
Java
@Take a look at void indexIsSoundHtml() { var mannequin = new TodoList(); var html = renderTemplate("/index.tmpl", mannequin); assertSoundHtml(html); } supply
Stage 2: testing HTML construction
What else ought to we take a look at?
We all know that the seems of a web page can solely be examined, finally, by a
human how it’s rendered in a browser. Nonetheless, there’s typically
logic in templates, and we would like to have the ability to take a look at that logic.
One is likely to be tempted to check the rendered HTML with string equality,
however this system fails in apply, as a result of templates comprise numerous
particulars that make string equality assertions impractical. The assertions
change into very verbose, and when studying the assertion, it turns into troublesome
to grasp what it’s that we’re attempting to show.
What we want
is a way to claim that some components of the rendered HTML
correspond to what we anticipate, and to ignore all the main points we do not
care about. A technique to do that is by working queries with the CSS selector language:
it’s a highly effective language that enables us to pick the
components that we care about from the entire HTML doc. As soon as we have now
chosen these components, we (1) rely that the variety of factor returned
is what we anticipate, and (2) that they comprise the textual content or different content material
that we anticipate.
The UI that we’re imagined to generate seems like this:
There are a number of particulars which are rendered dynamically:
- The variety of gadgets and their textual content content material change, clearly
- The type of the todo-item adjustments when it is accomplished (e.g., the
second) - The “2 gadgets left” textual content will change with the variety of non-completed
gadgets - One of many three buttons “All”, “Energetic”, “Accomplished” can be
highlighted, relying on the present url; as an illustration if we determine that the
url that exhibits solely the “Energetic” gadgets is /lively, then when the present url
is /lively, the “Energetic” button ought to be surrounded by a skinny purple
rectangle - The “Clear accomplished” button ought to solely be seen if any merchandise is
accomplished
Every of this considerations may be examined with the assistance of CSS selectors.
It is a snippet from the TodoMVC template (barely simplified). I
haven’t but added the dynamic bits, so what we see right here is static
content material, offered for instance:
index.tmpl
<part class="todoapp"> <ul class="todo-list"> <!-- These are right here simply to point out the construction of the listing gadgets --> <!-- Listing gadgets ought to get the category `accomplished` when marked as accomplished --> <li class="accomplished"> ② <div class="view"> <enter class="toggle" kind="checkbox" checked> <label>Style JavaScript</label> ① <button class="destroy"></button> </div> </li> <li> <div class="view"> <enter class="toggle" kind="checkbox"> <label>Purchase a unicorn</label> ① <button class="destroy"></button> </div> </li> </ul> <footer class="footer"> <!-- This ought to be `0 gadgets left` by default --> <span class="todo-count"><sturdy>0</sturdy> merchandise left</span> ⓷ <ul class="filters"> <li> <a class="chosen" href="#/">All</a> ④ </li> <li> <a href="#/lively">Energetic</a> </li> <li> <a href="#/accomplished">Accomplished</a> </li> </ul> <!-- Hidden if no accomplished gadgets are left ↓ --> <button class="clear-completed">Clear accomplished</button> ⑤ </footer> </part>
supply
By trying on the static model of the template, we are able to deduce which
CSS selectors can be utilized to establish the related components for the 5 dynamic
options listed above:
| characteristic | CSS selector |
| ① | All of the gadgets | ul.todo-list li |
| ② | Accomplished gadgets | ul.todo-list li.accomplished |
| ⓷ | Objects left | span.todo-count |
| ④ | Highlighted navigation hyperlink | ul.filters a.chosen |
| ⑤ | Clear accomplished button | button.clear-completed |
We are able to use these selectors to focus our checks on simply the issues we wish to take a look at.
Testing HTML content material
The primary take a look at will search for all of the gadgets, and show that the information
arrange by the take a look at is rendered accurately.
func Test_todoItemsAreShown(t *testing.T) { mannequin := todo.NewList() mannequin.Add("Foo") mannequin.Add("Bar") buf := renderTemplate(mannequin) // assert there are two <li> components contained in the <ul class="todo-list"> // assert the primary <li> textual content is "Foo" // assert the second <li> textual content is "Bar" } We want a approach to question the HTML doc with our CSS selector; a very good
library for Go is goquery, that implements an API impressed by jQuery.
In Java, we preserve utilizing the identical library we used to check for sound HTML, specifically
jsoup. Our take a look at turns into:
Go
func Test_todoItemsAreShown(t *testing.T) { mannequin := todo.NewList() mannequin.Add("Foo") mannequin.Add("Bar") buf := renderTemplate("index.tmpl", mannequin) // parse the HTML with goquery doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes())) if err != nil { // if parsing fails, we cease the take a look at right here with t.FatalF t.Fatalf("Error rendering template %s", err) } // assert there are two <li> components contained in the <ul class="todo-list"> choice := doc.Discover("ul.todo-list li") assert.Equal(t, 2, choice.Size()) // assert the primary <li> textual content is "Foo" assert.Equal(t, "Foo", textual content(choice.Nodes[0])) // assert the second <li> textual content is "Bar" assert.Equal(t, "Bar", textual content(choice.Nodes[1])) } func textual content(node *html.Node) string { // A bit of mess on account of the truth that goquery has // a .Textual content() technique on Choice however not on html.Node sel := goquery.Choice{Nodes: []*html.Node{node}} return strings.TrimSpace(sel.Textual content()) } supply
Java
@Take a look at void todoItemsAreShown() throws IOException { var mannequin = new TodoList(); mannequin.add("Foo"); mannequin.add("Bar"); var html = renderTemplate("/index.tmpl", mannequin); // parse the HTML with jsoup Doc doc = Jsoup.parse(html, ""); // assert there are two <li> components contained in the <ul class="todo-list"> var choice = doc.choose("ul.todo-list li"); assertThat(choice).hasSize(2); // assert the primary <li> textual content is "Foo" assertThat(choice.get(0).textual content()).isEqualTo("Foo"); // assert the second <li> textual content is "Bar" assertThat(choice.get(1).textual content()).isEqualTo("Bar"); } supply
If we nonetheless have not modified the template to populate the listing from the
mannequin, this take a look at will fail, as a result of the static template
todo gadgets have completely different textual content:
Go
--- FAIL: Test_todoItemsAreShown (0.00s) index_template_test.go:44: First listing merchandise: need Foo, received Style JavaScript index_template_test.go:49: Second listing merchandise: need Bar, received Purchase a unicorn
Java
IndexTemplateTest > todoItemsAreShown() FAILED org.opentest4j.AssertionFailedError: Anticipating: <"Style JavaScript"> to be equal to: <"Foo"> however was not.
We repair it by making the template use the mannequin knowledge:
Go
<ul class="todo-list"> {{ vary .Objects }} <li> <div class="view"> <enter class="toggle" kind="checkbox"> <label>{{ .Title }}</label> <button class="destroy"></button> </div> </li> {{ finish }} </ul> supply
Java – jmustache
<ul class="todo-list"> {{ #allItems }} <li> <div class="view"> <enter class="toggle" kind="checkbox"> <label>{{ title }}</label> <button class="destroy"></button> </div> </li> {{ /allItems }} </ul> supply
Take a look at each content material and soundness on the similar time
Our take a look at works, however it’s a bit verbose, particularly the Go model. If we will have extra
checks, they’ll change into repetitive and troublesome to learn, so we make it extra concise by extracting a helper perform for parsing the html. We additionally take away the
feedback, because the code ought to be clear sufficient
Go
func Test_todoItemsAreShown(t *testing.T) { mannequin := todo.NewList() mannequin.Add("Foo") mannequin.Add("Bar") buf := renderTemplate("index.tmpl", mannequin) doc := parseHtml(t, buf) choice := doc.Discover("ul.todo-list li") assert.Equal(t, 2, choice.Size()) assert.Equal(t, "Foo", textual content(choice.Nodes[0])) assert.Equal(t, "Bar", textual content(choice.Nodes[1])) } func parseHtml(t *testing.T, buf bytes.Buffer) *goquery.Doc { doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes())) if err != nil { // if parsing fails, we cease the take a look at right here with t.FatalF t.Fatalf("Error rendering template %s", err) } return doc } Java
@Take a look at void todoItemsAreShown() throws IOException { var mannequin = new TodoList(); mannequin.add("Foo"); mannequin.add("Bar"); var html = renderTemplate("/index.tmpl", mannequin); var doc = parseHtml(html); var choice = doc.choose("ul.todo-list li"); assertThat(choice).hasSize(2); assertThat(choice.get(0).textual content()).isEqualTo("Foo"); assertThat(choice.get(1).textual content()).isEqualTo("Bar"); } personal static Doc parseHtml(String html) { return Jsoup.parse(html, ""); } Significantly better! No less than in my view. Now that we extracted the parseHtml helper, it is
a good suggestion to verify for sound HTML within the helper:
Go
func parseHtml(t *testing.T, buf bytes.Buffer) *goquery.Doc { assertWellFormedHtml(t, buf) doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes())) if err != nil { // if parsing fails, we cease the take a look at right here with t.FatalF t.Fatalf("Error rendering template %s", err) } return doc } supply
Java
personal static Doc parseHtml(String html) { var parser = Parser.htmlParser().setTrackErrors(10); var doc = Jsoup.parse(html, "", parser); assertThat(parser.getErrors()).isEmpty(); return doc; } supply
And with this, we are able to do away with the primary take a look at that we wrote, as we are actually testing for sound HTML on a regular basis.
The second take a look at
Now we’re in a very good place for testing extra rendering logic. The
second dynamic characteristic in our listing is “Listing gadgets ought to get the category
accomplished when marked as accomplished”. We are able to write a take a look at for this:
Go
func Test_completedItemsGetCompletedClass(t *testing.T) { mannequin := todo.NewList() mannequin.Add("Foo") mannequin.AddCompleted("Bar") buf := renderTemplate("index.tmpl", mannequin) doc := parseHtml(t, buf) choice := doc.Discover("ul.todo-list li.accomplished") assert.Equal(t, 1, choice.Measurement()) assert.Equal(t, "Bar", textual content(choice.Nodes[0])) } supply
Java
@Take a look at void completedItemsGetCompletedClass() { var mannequin = new TodoList(); mannequin.add("Foo"); mannequin.addCompleted("Bar"); var html = renderTemplate("/index.tmpl", mannequin); Doc doc = Jsoup.parse(html, ""); var choice = doc.choose("ul.todo-list li.accomplished"); assertThat(choice).hasSize(1); assertThat(choice.textual content()).isEqualTo("Bar"); } supply
And this take a look at may be made inexperienced by including this little bit of logic to the
template:
Go
<ul class="todo-list"> {{ vary .Objects }} <li class="{{ if .IsCompleted }}accomplished{{ finish }}"> <div class="view"> <enter class="toggle" kind="checkbox"> <label>{{ .Title }}</label> <button class="destroy"></button> </div> </li> {{ finish }} </ul> supply
Java – jmustache
<ul class="todo-list"> {{ #allItems }} <li class="{{ #isCompleted }}accomplished{{ /isCompleted }}"> <div class="view"> <enter class="toggle" kind="checkbox"> <label>{{ title }}</label> <button class="destroy"></button> </div> </li> {{ /allItems }} </ul> supply
So little by little, we are able to take a look at and add the varied dynamic options
that our template ought to have.
Make it simple so as to add new checks
The primary of the 20 ideas from the wonderful discuss by Russ Cox on Go
Testing is “Make it simple so as to add new take a look at instances“. Certainly, in Go there
is a bent to make most checks parameterized, for this very motive.
Then again, whereas Java has
good assist
for parameterized checks with JUnit 5, they are not used as a lot.
Since our present two checks have the identical construction, we
may issue them right into a single parameterized take a look at.
A take a look at case for us will encompass:
- A reputation (in order that we are able to produce clear error messages when the take a look at
fails) - A mannequin (in our case a
todo.Listing) - A CSS selector
- A listing of textual content matches that we look forward to finding after we run the CSS
selector on the rendered HTML.
So that is the information construction for our take a look at instances:
Go
var testCases = []struct { identify string mannequin *todo.Listing selector string matches []string }{ { identify: "all todo gadgets are proven", mannequin: todo.NewList(). Add("Foo"). Add("Bar"), selector: "ul.todo-list li", matches: []string{"Foo", "Bar"}, }, { identify: "accomplished gadgets get the 'accomplished' class", mannequin: todo.NewList(). Add("Foo"). AddCompleted("Bar"), selector: "ul.todo-list li.accomplished", matches: []string{"Bar"}, }, } supply
Java
report TestCase(String identify, TodoList mannequin, String selector, Listing<String> matches) { @Override public String toString() { return identify; } } public static TestCase[] indexTestCases() { return new TestCase[]{ new TestCase( "all todo gadgets are proven", new TodoList() .add("Foo") .add("Bar"), "ul.todo-list li", Listing.of("Foo", "Bar")), new TestCase( "accomplished gadgets get the 'accomplished' class", new TodoList() .add("Foo") .addCompleted("Bar"), "ul.todo-list li.accomplished", Listing.of("Bar")), }; } supply
And that is our parameterized take a look at:
Go
func Test_indexTemplate(t *testing.T) { for _, take a look at := vary testCases { t.Run(take a look at.identify, func(t *testing.T) { buf := renderTemplate("index.tmpl", take a look at.mannequin) assertWellFormedHtml(t, buf) doc := parseHtml(t, buf) choice := doc.Discover(take a look at.selector) require.Equal(t, len(take a look at.matches), len(choice.Nodes), "surprising # of matches") for i, node := vary choice.Nodes { assert.Equal(t, take a look at.matches[i], textual content(node)) } }) } } supply
Java
@ParameterizedTest @MethodSource("indexTestCases") void testIndexTemplate(TestCase take a look at) { var html = renderTemplate("/index.tmpl", take a look at.mannequin); var doc = parseHtml(html); var choice = doc.choose(take a look at.selector); assertThat(choice).hasSize(take a look at.matches.measurement()); for (int i = 0; i < take a look at.matches.measurement(); i++) { assertThat(choice.get(i).textual content()).isEqualTo(take a look at.matches.get(i)); } } supply
We are able to now run our parameterized take a look at and see it cross:
Go
$ go take a look at -v === RUN Test_indexTemplate === RUN Test_indexTemplate/all_todo_items_are_shown === RUN Test_indexTemplate/completed_items_get_the_'accomplished'_class --- PASS: Test_indexTemplate (0.00s) --- PASS: Test_indexTemplate/all_todo_items_are_shown (0.00s) --- PASS: Test_indexTemplate/completed_items_get_the_'accomplished'_class (0.00s) PASS okay tdd-html-templates 0.608s
Java
$ ./gradlew take a look at > Activity :take a look at IndexTemplateTest > testIndexTemplate(TestCase) > [1] all todo gadgets are proven PASSED IndexTemplateTest > testIndexTemplate(TestCase) > [2] accomplished gadgets get the 'accomplished' class PASSED
Word how, by giving a reputation to our take a look at instances, we get very readable take a look at output, each on the terminal and within the IDE:
Having rewritten our two previous checks in desk kind, it is now tremendous simple so as to add
one other. That is the take a look at for the “x gadgets left” textual content:
Go
{ identify: "gadgets left", mannequin: todo.NewList(). Add("One"). Add("Two"). AddCompleted("Three"), selector: "span.todo-count", matches: []string{"2 gadgets left"}, }, supply
Java
new TestCase( "gadgets left", new TodoList() .add("One") .add("Two") .addCompleted("Three"), "span.todo-count", Listing.of("2 gadgets left")), supply
And the corresponding change within the html template is:
Go
<span class="todo-count"><sturdy>{{len .ActiveItems}}</sturdy> gadgets left</span> supply
Java – jmustache
<span class="todo-count"><sturdy>{{activeItemsCount}}</sturdy> gadgets left</span> supply
The above change within the template requires a supporting technique within the mannequin:
Go
kind Merchandise struct { Title string IsCompleted bool } kind Listing struct { Objects []*Merchandise } func (l *Listing) ActiveItems() []*Merchandise { var consequence []*Merchandise for _, merchandise := vary l.Objects { if !merchandise.IsCompleted { consequence = append(consequence, merchandise) } } return consequence } supply
Java
public class TodoList { personal last Listing<TodoItem> gadgets = new ArrayList<>(); // ... public lengthy activeItemsCount() { return gadgets.stream().filter(TodoItem::isActive).rely(); } } supply
We have invested just a little effort in our testing infrastructure, in order that including new
take a look at instances is less complicated. Within the subsequent part, we’ll see that the necessities
for the following take a look at instances will push us to refine our take a look at infrastructure additional.
Making the desk extra expressive, on the expense of the take a look at code
We are going to now take a look at the “All”, “Energetic” and “Accomplished” navigation hyperlinks at
the underside of the UI (see the image above),
and these rely upon which url we’re visiting, which is
one thing that our template has no approach to discover out.
At present, all we cross to our template is our mannequin, which is a todo-list.
It is not appropriate so as to add the presently visited url to the mannequin, as a result of that’s
consumer navigation state, not utility state.
So we have to cross extra info to the template past the mannequin. A simple manner
is to cross a map, which we assemble in our
renderTemplate perform:
Go
func renderTemplate(mannequin *todo.Listing, path string) bytes.Buffer { templ := template.Should(template.ParseFiles("index.tmpl")) var buf bytes.Buffer knowledge := map[string]any{ "mannequin": mannequin, "path": path, } err := templ.Execute(&buf, knowledge) if err != nil { panic(err) } return buf } Java
personal String renderTemplate(String templateName, TodoList mannequin, String path) { var template = Mustache.compiler().compile( new InputStreamReader( getClass().getResourceAsStream(templateName))); var knowledge = Map.of( "mannequin", mannequin, "path", path ); return template.execute(knowledge); } And correspondingly our take a look at instances desk has yet one more discipline:
Go
var testCases = []struct { identify string mannequin *todo.Listing path string selector string matches []string }{ { identify: "all todo gadgets are proven", mannequin: todo.NewList(). Add("Foo"). Add("Bar"), selector: "ul.todo-list li", matches: []string{"Foo", "Bar"}, }, // ... the opposite instances { identify: "highlighted navigation hyperlink: All", path: "/", selector: "ul.filters a.chosen", matches: []string{"All"}, }, { identify: "highlighted navigation hyperlink: Energetic", path: "/lively", selector: "ul.filters a.chosen", matches: []string{"Energetic"}, }, { identify: "highlighted navigation hyperlink: Accomplished", path: "/accomplished", selector: "ul.filters a.chosen", matches: []string{"Accomplished"}, }, } Java
report TestCase(String identify, TodoList mannequin, String path, String selector, Listing<String> matches) { @Override public String toString() { return identify; } } public static TestCase[] indexTestCases() { return new TestCase[]{ new TestCase( "all todo gadgets are proven", new TodoList() .add("Foo") .add("Bar"), "/", "ul.todo-list li", Listing.of("Foo", "Bar")), // ... the earlier instances new TestCase( "highlighted navigation hyperlink: All", new TodoList(), "/", "ul.filters a.chosen", Listing.of("All")), new TestCase( "highlighted navigation hyperlink: Energetic", new TodoList(), "/lively", "ul.filters a.chosen", Listing.of("Energetic")), new TestCase( "highlighted navigation hyperlink: Accomplished", new TodoList(), "/accomplished", "ul.filters a.chosen", Listing.of("Accomplished")), }; } We discover that for the three new instances, the mannequin is irrelevant;
whereas for the earlier instances, the trail is irrelevant. The Go syntax permits us
to initialize a struct with simply the fields we’re serious about, however Java doesn’t have
the same characteristic, so we’re pushed to cross additional info, and this makes the take a look at instances
desk more durable to grasp.
A developer may take a look at the primary take a look at case and surprise if the anticipated conduct relies upon
on the trail being set to "/", and is likely to be tempted so as to add extra instances with
a distinct path. In the identical manner, when studying the
highlighted navigation hyperlink take a look at instances, the developer may surprise if the
anticipated conduct is dependent upon the mannequin being set to an empty todo listing. If that’s the case, one may
be led so as to add irrelevant take a look at instances for the highlighted hyperlink with non-empty todo-lists.
We wish to optimize for the time of the builders, so it is worthwhile to keep away from including irrelevant
knowledge to our take a look at case. In Java we would cross null for the
irrelevant fields, however there’s a greater manner: we are able to use
the builder sample,
popularized by Joshua Bloch.
We are able to shortly write one for the Java TestCase report this manner:
Java
report TestCase(String identify, TodoList mannequin, String path, String selector, Listing<String> matches) { @Override public String toString() { return identify; } public static last class Builder { String identify; TodoList mannequin; String path; String selector; Listing<String> matches; public Builder identify(String identify) { this.identify = identify; return this; } public Builder mannequin(TodoList mannequin) { this.mannequin = mannequin; return this; } public Builder path(String path) { this.path = path; return this; } public Builder selector(String selector) { this.selector = selector; return this; } public Builder matches(String ... matches) { this.matches = Arrays.asList(matches); return this; } public TestCase construct() { return new TestCase(identify, mannequin, path, selector, matches); } } } Hand-coding builders is just a little tedious, however doable, although there are
automated methods to put in writing them.
Now we are able to rewrite our Java take a look at instances with the Builder, to
obtain better readability:
Java
public static TestCase[] indexTestCases() { return new TestCase[]{ new TestCase.Builder() .identify("all todo gadgets are proven") .mannequin(new TodoList() .add("Foo") .add("Bar")) .selector("ul.todo-list li") .matches("Foo", "Bar") .construct(), // ... different instances new TestCase.Builder() .identify("highlighted navigation hyperlink: Accomplished") .path("/accomplished") .selector("ul.filters a.chosen") .matches("Accomplished") .construct(), }; } So, the place are we with our checks? At current, they fail for the improper motive: null-pointer exceptions
as a result of lacking mannequin and path values.
In an effort to get our new take a look at instances to fail for the precise motive, specifically that the template does
not but have logic to spotlight the right hyperlink, we should
present default values for mannequin and path. In Go, we are able to do that
within the take a look at technique:
Go
func Test_indexTemplate(t *testing.T) { for _, take a look at := vary testCases { t.Run(take a look at.identify, func(t *testing.T) { if take a look at.mannequin == nil { take a look at.mannequin = todo.NewList() } buf := renderTemplate(take a look at.mannequin, take a look at.path) // ... similar as earlier than }) } } supply
In Java, we are able to present default values within the builder:
Java
public static last class Builder { String identify; TodoList mannequin = new TodoList(); String path = "/"; String selector; Listing<String> matches; // ... } supply
With these adjustments, we see that the final two take a look at instances, those for the highlighted hyperlink Energetic
and Accomplished fail, for the anticipated motive that the highlighted hyperlink doesn’t change:
Go
=== RUN Test_indexTemplate/highlighted_navigation_link:_Active index_template_test.go:82: Error Hint: .../tdd-templates/go/index_template_test.go:82 Error: Not equal: anticipated: "Energetic" precise : "All" === RUN Test_indexTemplate/highlighted_navigation_link:_Completed index_template_test.go:82: Error Hint: .../tdd-templates/go/index_template_test.go:82 Error: Not equal: anticipated: "Accomplished" precise : "All"
Java
IndexTemplateTest > testIndexTemplate(TestCase) > [5] highlighted navigation hyperlink: Energetic FAILED org.opentest4j.AssertionFailedError: Anticipating: <"All"> to be equal to: <"Energetic"> however was not. IndexTemplateTest > testIndexTemplate(TestCase) > [6] highlighted navigation hyperlink: Accomplished FAILED org.opentest4j.AssertionFailedError: Anticipating: <"All"> to be equal to: <"Accomplished"> however was not.
To make the checks cross, we make these adjustments to the template:
Go
<ul class="filters"> <li> <a class="{{ if eq .path "/" }}chosen{{ finish }}" href="#/">All</a> </li> <li> <a class="{{ if eq .path "/lively" }}chosen{{ finish }}" href="#/lively">Energetic</a> </li> <li> <a class="{{ if eq .path "/accomplished" }}chosen{{ finish }}" href="#/accomplished">Accomplished</a> </li> </ul> supply
Java – jmustache
<ul class="filters"> <li> <a class="{{ #pathRoot }}chosen{{ /pathRoot }}" href="#/">All</a> </li> <li> <a class="{{ #pathActive }}chosen{{ /pathActive }}" href="#/lively">Energetic</a> </li> <li> <a class="{{ #pathCompleted }}chosen{{ /pathCompleted }}" href="#/accomplished">Accomplished</a> </li> </ul> supply
Because the Mustache template language doesn’t permit for equality testing, we should change the
knowledge handed to the template in order that we execute the equality checks earlier than rendering the template:
Java
personal String renderTemplate(String templateName, TodoList mannequin, String path) { var template = Mustache.compiler().compile( new InputStreamReader( getClass().getResourceAsStream(templateName))); var knowledge = Map.of( "mannequin", mannequin, "pathRoot", path.equals("/"), "pathActive", path.equals("/lively"), "pathCompleted", path.equals("/accomplished") ); return template.execute(knowledge); } supply
And with these adjustments, all of our checks now cross.
To recap this part, we made the take a look at code just a little bit extra difficult, in order that the take a look at
instances are clearer: it is a superb tradeoff!
Stage 3: testing HTML behaviour
Within the story up to now, we examined the behaviour of the HTML
templates, by checking the construction of the generated HTML.
That is good, however what if we needed to check the behaviour of the HTML
itself, plus any CSS and JavaScript it might use?
The behaviour of HTML by itself is normally fairly apparent, as a result of
there’s not a lot of it. The one components that may work together with the
consumer are the anchor (<a>), <kind> and
<enter> components, however the image adjustments fully when
we add CSS, that may cover, present, transfer round issues and plenty extra, and
with JavaScript, that may add any behaviour to a web page.
In an utility that’s primarily rendered server-side, we anticipate
that almost all behaviour is applied by returning new HTML with a
round-trip to the consumer, and this may be examined adequately with the
strategies we have seen up to now, however what if we needed to hurry up the
utility behaviour with a library similar to HTMX? This library works by particular
attributes which are added to components so as to add Ajax behaviour. These
attributes are in impact a DSL that we would wish to
take a look at.
How can we take a look at the mixture of HTML, CSS and JavaScript in
a unit take a look at?
Testing HTML, CSS and JavaScript requires one thing that is ready to
interpret and execute their behaviours; in different phrases, we want a
browser! It’s customary to make use of headless browsers in end-to-end checks;
can we use them for unitary checks as a substitute? I believe that is potential,
utilizing the next strategies, though I have to admit I’ve but to strive
this on an actual challenge.
We are going to use the Playwright
library, that’s accessible for each Go and
Java. The checks we
are going to put in writing can be slower, as a result of we must wait a number of
seconds for the headless browser to begin, however will retain a few of the
vital traits of unit checks, primarily that we’re testing
simply the HTML (and any related CSS and JavaScript), in isolation from
some other server-side logic.
Persevering with with the TodoMVC
instance, the following factor we would wish to take a look at is what occurs when the
consumer clicks on the checkbox of a todo merchandise. What we might wish to occur is
that:
- A POST name to the server is made, in order that the appliance is aware of
that the state of a todo merchandise has modified - The server returns new HTML for the dynamic a part of the web page,
specifically the entire part with class “todoapp”, in order that we are able to present the
new state of the appliance together with the rely of remaining “lively”
gadgets (see the template above) - The web page replaces the previous contents of the “todoapp” part with
the brand new ones.
Loading the web page within the Playwright browser
We begin with a take a look at that can simply load the preliminary HTML. The take a look at
is just a little concerned, so I present the whole code right here, after which I’ll
remark it little by little.
Go
func Test_toggleTodoItem(t *testing.T) { // render the preliminary HTML mannequin := todo.NewList(). Add("One"). Add("Two") initialHtml := renderTemplate("index.tmpl", mannequin, "/") // open the browser web page with Playwright web page := openPage() defer web page.Shut() logActivity(web page) // stub community calls err := web page.Route("**", func(route playwright.Route) { if route.Request().URL() == "http://localhost:4567/index.html" { // serve the preliminary HTML stubResponse(route, initialHtml.String(), "textual content/html") } else { // keep away from surprising requests panic("surprising request: " + route.Request().URL()) } }) if err != nil { t.Deadly(err) } // load preliminary HTML within the web page response, err := web page.Goto("http://localhost:4567/index.html") if err != nil { t.Deadly(err) } if response.Standing() != 200 { t.Fatalf("surprising standing: %d", response.Standing()) } } supply
Java
public class IndexBehaviourTest { static Playwright playwright; static Browser browser; @BeforeAll static void launchBrowser() { playwright = Playwright.create(); browser = playwright.chromium().launch(); } @AfterAll static void closeBrowser() { playwright.shut(); } @Take a look at void toggleTodoItem() { // Render the preliminary html TodoList mannequin = new TodoList() .add("One") .add("Two"); String initialHtml = renderTemplate("/index.tmpl", mannequin, "/"); strive (Web page web page = browser.newPage()) { logActivity(web page); // stub community calls web page.route("**", route -> { if (route.request().url().equals("http://localhost:4567/index.html")) { // serve the preliminary HTML route.fulfill(new Route.FulfillOptions() .setContentType("textual content/html") .setBody(initialHtml)); } else { // we do not need surprising calls fail(String.format("Sudden request: %s %s", route.request().technique(), route.request().url())); } }); // load preliminary html web page.navigate("http://localhost:4567/index.html"); } } } supply
At first of the take a look at, we initialize the mannequin with two todo
gadgets “One” and “Two”, then we render the template as earlier than:
Go
mannequin := todo.NewList(). Add("One"). Add("Two") initialHtml := renderTemplate("index.tmpl", mannequin, "/") Java
TodoList mannequin = new TodoList() .add("One") .add("Two"); String initialHtml = renderTemplate("/index.tmpl", mannequin, "/"); Then we open the Playwright “web page”, which is able to begin a headless
browser
Go
web page := openPage() defer web page.Shut() logActivity(web page)
Java
strive (Web page web page = browser.newPage()) { logActivity(web page); The openPage perform in Go returns a Playwright
Web page object,
Go
func openPage() playwright.Web page { pw, err := playwright.Run() if err != nil { log.Fatalf("couldn't begin playwright: %v", err) } browser, err := pw.Chromium.Launch() if err != nil { log.Fatalf("couldn't launch browser: %v", err) } web page, err := browser.NewPage() if err != nil { log.Fatalf("couldn't create web page: %v", err) } return web page } and the logActivity perform gives suggestions on what
the web page is doing
Go
func logActivity(web page playwright.Web page) { web page.OnRequest(func(request playwright.Request) { log.Printf(">> %s %sn", request.Technique(), request.URL()) }) web page.OnResponse(func(response playwright.Response) { log.Printf("<< %d %sn", response.Standing(), response.URL()) }) web page.OnLoad(func(web page playwright.Web page) { log.Println("Loaded: " + web page.URL()) }) web page.OnConsole(func(message playwright.ConsoleMessage) { log.Println("! " + message.Textual content()) }) } Java
personal void logActivity(Web page web page) { web page.onRequest(request -> System.out.printf(">> %s %spercentn", request.technique(), request.url())); web page.onResponse(response -> System.out.printf("<< %s %spercentn", response.standing(), response.url())); web page.onLoad(page1 -> System.out.println("Loaded: " + page1.url())); web page.onConsoleMessage(consoleMessage -> System.out.println("! " + consoleMessage.textual content())); } Then we stub all community exercise that the web page may attempt to do
Go
err := web page.Route("**", func(route playwright.Route) { if route.Request().URL() == "http://localhost:4567/index.html" { // serve the preliminary HTML stubResponse(route, initialHtml.String(), "textual content/html") } else { // keep away from surprising requests panic("surprising request: " + route.Request().URL()) } }) Java
// stub community calls web page.route("**", route -> { if (route.request().url().equals("http://localhost:4567/index.html")) { // serve the preliminary HTML route.fulfill(new Route.FulfillOptions() .setContentType("textual content/html") .setBody(initialHtml)); } else { // we do not need surprising calls fail(String.format("Sudden request: %s %s", route.request().technique(), route.request().url())); } }); and we ask the web page to load the preliminary HTML
Go
response, err := web page.Goto("http://localhost:4567/index.html") Java
web page.navigate("http://localhost:4567/index.html"); With all this equipment in place, we run the take a look at; it succeeds and
it logs the stubbed community exercise on normal output:
Go
=== RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html Loaded: http://localhost:4567/index.html --- PASS: Test_toggleTodoItem (0.89s)
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html Loaded: http://localhost:4567/index.html IndexBehaviourTest > toggleTodoItem() PASSED
So with this take a look at we are actually capable of load arbitrary HTML in a
headless browser. Within the subsequent sections we’ll see methods to simulate consumer
interplay with components of the web page, and observe the web page’s
behaviour. However first we have to remedy an issue with the dearth of
identifiers in our area mannequin.
Figuring out todo gadgets
Now we wish to click on on the “One” checkbox. The issue we have now is
that at current, we have now no approach to establish particular person todo gadgets, so
we introduce an Id discipline within the todo merchandise:
Go – up to date mannequin with Id
kind Merchandise struct { Id int Title string IsCompleted bool } func (l *Listing) AddWithId(id int, title string) *Listing { merchandise := Merchandise{ Id: id, Title: title, } l.Objects = append(l.Objects, &merchandise) return l } // Add creates a brand new todo.Merchandise with a random Id func (l *Listing) Add(title string) *Listing { merchandise := Merchandise{ Id: generateRandomId(), Title: title, } l.Objects = append(l.Objects, &merchandise) return l } func generateRandomId() int { return abs(rand.Int()) } Java – up to date mannequin with Id
public class TodoList { personal last Listing<TodoItem> gadgets = new ArrayList<>(); public TodoList add(String title) { gadgets.add(new TodoItem(generateRandomId(), title, false)); return this; } public TodoList addCompleted(String title) { gadgets.add(new TodoItem(generateRandomId(), title, true)); return this; } public TodoList add(int id, String title) { gadgets.add(new TodoItem(id, title, false)); return this; } personal static int generateRandomId() { return new Random().nextInt(0, Integer.MAX_VALUE); } } public report TodoItem(int id, String title, boolean isCompleted) { public boolean isActive() { return !isCompleted; } } And we replace the mannequin in our take a look at so as to add specific Ids
Go – including Id within the take a look at knowledge
func Test_toggleTodoItem(t *testing.T) { // render the preliminary HTML mannequin := todo.NewList(). AddWithId(101, "One"). AddWithId(102, "Two") initialHtml := renderTemplate("index.tmpl", mannequin, "/") // ... } Java – including Id within the take a look at knowledge
@Take a look at void toggleTodoItem() { // Render the preliminary html TodoList mannequin = new TodoList() .add(101, "One") .add(102, "Two"); String initialHtml = renderTemplate("/index.tmpl", mannequin, "/"); } We are actually prepared to check consumer interplay with the web page.
Clicking on a todo merchandise
We wish to simulate consumer interplay with the HTML web page. It is likely to be
tempting to proceed to make use of CSS selectors to establish the particular
checkbox that we wish to click on, however there’s a greater manner: there’s a
consensus amongst front-end builders that one of the simplest ways to check
interplay with a web page is to make use of it
the identical manner that customers do. As an illustration, you do not search for a
button by a CSS locator similar to button.purchase; as a substitute,
you search for one thing clickable with the label “Purchase”. In apply,
this implies figuring out components of the web page by their
ARIA roles.
To this finish, we add code to our take a look at to search for a checkbox labelled
“One”:
Go
func Test_toggleTodoItem(t *testing.T) { // ... // click on on the "One" checkbox checkbox := web page.GetByRole(*playwright.AriaRoleCheckbox, playwright.PageGetByRoleOptions{Title: "One"}) if err := checkbox.Click on(); err != nil { t.Deadly(err) } } Java
@Take a look at void toggleTodoItem() { // ... // click on on the "One" checkbox var checkbox = web page.getByRole(AriaRole.CHECKBOX, new Web page.GetByRoleOptions().setName("One")); checkbox.click on(); } } We run the take a look at, and it fails:
Go
>> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html Loaded: http://localhost:4567/index.html --- FAIL: Test_toggleTodoItem (32.74s) index_behaviour_test.go:50: playwright: timeout: Timeout 30000ms exceeded.
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html Loaded: http://localhost:4567/index.html IndexBehaviourTest > toggleTodoItem() FAILED com.microsoft.playwright.TimeoutError: Error { message="hyperlink the label to the checkbox correctly: generated HTML with unhealthy accessibility
<li> <div class="view"> <enter class="toggle" kind="checkbox"> <label>One</label> <button class="destroy"></button> </div> </li>
We repair it by utilizing the for attribute within the
template,
index.tmpl – Go
<li> <div class="view"> <enter id="checkbox-{{.Id}}" class="toggle" kind="checkbox"> <label for="checkbox-{{.Id}}">{{.Title}}</label> <button class="destroy"></button> </div> </li> index.tmpl – Java
<li> <div class="view"> <enter id="checkbox-{{ id }}" class="toggle" kind="checkbox"> <label for="checkbox-{{ id }}">{{ title }}</label> <button class="destroy"></button> </div> </li> In order that it generates correct, accessible HTML:
generated HTML with higher accessibility
<li> <div class="view"> <enter id="checkbox-101" class="toggle" kind="checkbox"> <label for="checkbox-101">One</label> <button class="destroy"></button> </div> </li>
We run once more the take a look at, and it passes.
On this part we noticed how testing the HTML in the identical was as customers
work together with it led us to make use of ARIA roles, which led to enhancing
accessibility of our generated HTML. Within the subsequent part, we are going to see
methods to take a look at that the clicking on a todo merchandise triggers a distant name to the
server, that ought to lead to swapping part of the present HTML with
the HTML returned by the XHR name.
Spherical-trip to the server
Now we are going to lengthen our take a look at. We inform the take a look at that if name to
POST /toggle/101 is obtained, it ought to return some
stubbed HTML.
Go
} else if route.Request().URL() == "http://localhost:4567/toggle/101" && route.Request().Technique() == "POST" { // we anticipate {that a} POST /toggle/101 request is made after we click on on the "One" checkbox const stubbedHtml = ` <part class="todoapp"> <p>Stubbed html</p> </part>` stubResponse(route, stubbedHtml, "textual content/html") Java
} else if (route.request().url().equals("http://localhost:4567/toggle/101") && route.request().technique().equals("POST")) { // we anticipate {that a} POST /toggle/101 request is made after we click on on the "One" checkbox String stubbedHtml = """ <part class="todoapp"> <p>Stubbed html</p> </part> """; route.fulfill(new Route.FulfillOptions() .setContentType("textual content/html") .setBody(stubbedHtml)); And we stub the loading of the HTMX library, which we load from a
native file:
Go
} else if route.Request().URL() == "https://unpkg.com/htmx.org@1.9.12" { // serve the htmx library stubResponse(route, readFile("testdata/htmx.min.js"), "utility/javascript") Go
} else if (route.request().url().equals("https://unpkg.com/htmx.org@1.9.12")) { // serve the htmx library route.fulfill(new Route.FulfillOptions() .setContentType("textual content/html") .setBody(readFile("/htmx.min.js"))); Lastly, we add the expectation that, after we click on the checkbox,
the part of the HTML that comprises a lot of the utility is
reloaded.
Go
// click on on the "One" checkbox checkbox := web page.GetByRole(*playwright.AriaRoleCheckbox, playwright.PageGetByRoleOptions{Title: "One"}) if err := checkbox.Click on(); err != nil { t.Deadly(err) } // verify that the web page has been up to date doc := parseHtml(t, content material(t, web page)) components := doc.Discover("physique > part.todoapp > p") assert.Equal(t, "Stubbed html", components.Textual content(), should(web page.Content material())) java
// click on on the "One" checkbox var checkbox = web page.getByRole(AriaRole.CHECKBOX, new Web page.GetByRoleOptions().setName("One")); checkbox.click on(); // verify that the web page has been up to date var doc = parseHtml(web page.content material()); var components = doc.choose("physique > part.todoapp > p"); assertThat(components.textual content()) .describedAs(web page.content material()) .isEqualTo("Stubbed html"); We run the take a look at, and it fails, as anticipated. In an effort to perceive
why precisely it fails, we add to the error message the entire HTML
doc.
Go
assert.Equal(t, "Stubbed html", components.Textual content(), should(web page.Content material()))
Java
assertThat(components.textual content()) .describedAs(web page.content material()) .isEqualTo("Stubbed html"); The error message may be very verbose, however we see that the rationale it
fails is that we do not see the stubbed HTML within the output. This implies
that the web page didn’t make the anticipated XHR name.
Go – Java is comparable
--- FAIL: Test_toggleTodoItem (2.75s) === RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html Loaded: http://localhost:4567/index.html index_behaviour_test.go:67: Error Hint: .../index_behaviour_test.go:67 Error: Not equal: anticipated: "Stubbed html" precise : "" ... Take a look at: Test_toggleTodoItem Messages: <!DOCTYPE html><html lang="en"><head> <meta charset="utf-8"> <meta identify="viewport" content material="width=device-width, initial-scale=1"> <title>Template • TodoMVC</title> <script src="https://unpkg.com/htmx.org@1.9.12"></script> <physique> <part class="todoapp"> ... <li class=""> <div class="view"> <enter id="checkbox-101" class="toggle" kind="checkbox"> <label for="checkbox-101">One</label> <button class="destroy"></button> </div> </li> ...
We are able to make this take a look at cross by altering the HTML template to make use of HTMX
to make an XHR name again to the server. First we load the HTMX
library:
index.tmpl
<title>Template • TodoMVC</title> <script src="https://unpkg.com/htmx.org@1.9.12"></script>
Then we add the HTMX attributes to the checkboxes:
index.tmpl
<enter data-hx-post="/toggle/{{.Id}}" data-hx-target="part.todoapp" id="checkbox-{{.Id}}" class="toggle" kind="checkbox"> The data-hx-post annotation will make HTMX do a POST
name to the required url. The data-hx-target tells HTMX
to repeat the HTML returned by the decision, to the factor specified by the
part.todoapp CSS locator.
We run once more the take a look at, and it nonetheless fails!
Go – Java is comparable
--- FAIL: Test_toggleTodoItem (2.40s) === RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html >> GET https://unpkg.com/htmx.org@1.9.12 << 200 https://unpkg.com/htmx.org@1.9.12 Loaded: http://localhost:4567/index.html >> POST http://localhost:4567/toggle/101 << 200 http://localhost:4567/toggle/101 index_behaviour_test.go:67: Error Hint: .../index_behaviour_test.go:67 Error: Not equal: anticipated: "Stubbed html" precise : "" ... Take a look at: Test_toggleTodoItem Messages: <!DOCTYPE html><html lang="en"><head> <meta charset="utf-8"> <meta identify="viewport" content material="width=device-width, initial-scale=1"> <title>Template • TodoMVC</title> <script src="https://unpkg.com/htmx.org@1.9.12"></script> ... <physique> <part class="todoapp"><part class="todoapp"> <p>Stubbed html</p> </part></part> ... </physique></html>
The log strains present that the POST name occurred as anticipated, however
examination of the error message exhibits that the HTML construction we
anticipated will not be there: we have now a part.todoapp nested
inside one other. Which means that we’re not utilizing the HTMX annotations
accurately, and exhibits why this sort of take a look at may be useful. We add the
lacking annotation
index.tmpl
<enter data-hx-post="/toggle/{{.Id}}" data-hx-target="part.todoapp" data-hx-swap="outerHTML" id="checkbox-{{.Id}}" class="toggle" kind="checkbox"> The default behaviour of HTMX is to switch the inside HTML of the
goal factor. The data-hx-swap="outerHTML" annotation
tells HTMX to switch the outer HTML as a substitute.
and we take a look at once more, and this time it passes!
Go
=== RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html >> GET https://unpkg.com/htmx.org@1.9.12 << 200 https://unpkg.com/htmx.org@1.9.12 Loaded: http://localhost:4567/index.html >> POST http://localhost:4567/toggle/101 << 200 http://localhost:4567/toggle/101 --- PASS: Test_toggleTodoItem (1.39s)
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html >> GET https://unpkg.com/htmx.org@1.9.12 << 200 https://unpkg.com/htmx.org@1.9.12 Loaded: http://localhost:4567/index.html >> POST http://localhost:4567/toggle/101 << 200 http://localhost:4567/toggle/101 IndexBehaviourTest > toggleTodoItem() PASSED
On this part we noticed methods to write a take a look at for the behaviour of our
HTML that, whereas utilizing the difficult equipment of a headless browser,
nonetheless feels extra like a unit take a look at than an integration take a look at. It’s in
reality testing simply an HTML web page with any related CSS and JavaScript,
in isolation from different components of the appliance similar to controllers,
providers or repositories.
The take a look at prices 2-3 seconds of ready time for the headless browser to return up, which is normally an excessive amount of for a unit take a look at; nonetheless, like a unit take a look at, it is rather secure, as it isn’t flaky, and its failures are documented with a comparatively clear error message.
See the ultimate model of the take a look at in Go and in Java.
Bonus degree: Stringly asserted
Esko Luontola, TDD knowledgeable and creator of the net course tdd.mooc.fi, urged an alternate to testing HTML with CSS selectors: the concept is to rework HTML right into a human-readable canonical kind.
Let’s take for instance this snippet of generated HTML:
<ul class="todo-list"> <li class=""> <div class="view"> <enter id="checkbox-100" class="toggle" kind="checkbox"> <label for="checkbox-100">One</label> <button class="destroy"></button> </div> </li> <li class=""> <div class="view"> <enter id="checkbox-200" class="toggle" kind="checkbox"> <label for="checkbox-200">Two</label> <button class="destroy"></button> </div> </li> <li class="accomplished"> <div class="view"> <enter id="checkbox-300" class="toggle" kind="checkbox"> <label for="checkbox-300">Three</label> <button class="destroy"></button> </div> </li> </ul>
We may visualize the above HTML by:
- deleting all HTML tags
- lowering each sequence of whitespace characters to a single clean
to reach at:
One Two Three
This, nonetheless, removes an excessive amount of of the HTML construction to be helpful. As an illustration, it doesn’t allow us to distinguish between lively and accomplished gadgets. Some HTML factor signify seen content material: as an illustration
<enter worth="foo" />
exhibits a textual content field with the phrase “foo” that is a crucial a part of the manner we understand HTML. To visualise these components, Esko suggests so as to add a data-test-icon attribute that provides some textual content for use rather than the factor when visualizing it for testing. With this,
<enter worth="foo" data-test-icon="[foo]" />
the enter factor is visualized as [foo], with the sq. brackets hinting that the phrase “foo” sits inside an editable textual content field. Now if we add test-icons to our HTML template,
Go — Java is comparable
<ul class="todo-list"> {{ vary .mannequin.AllItems }} <li class="{{ if .IsCompleted }}accomplished{{ finish }}"> <div class="view"> <enter data-hx-post="/toggle/{{ .Id }}" data-hx-target="part.todoapp" data-hx-swap="outerHTML" id="checkbox-{{ .Id }}" class="toggle" kind="checkbox" data-test-icon="{{ if .IsCompleted }}✅{{ else }}⬜{{ finish }}"> <label for="checkbox-{{ .Id }}">{{ .Title }}</label> <button class="destroy" data-test-icon="❌️"></button> </div> </li> {{ finish }} </ul> we are able to assert towards its canonical visible illustration like this:
Go
func Test_visualize_html_example(t *testing.T) { mannequin := todo.NewList(). Add("One"). Add("Two"). AddCompleted("Three") buf := renderTemplate("todo-list.tmpl", mannequin, "/") anticipated := ` ⬜ One ❌️ ⬜ Two ❌️ ✅ Three ❌️ ` assert.Equal(t, normalizeWhitespace(anticipated), visualizeHtml(buf.String())) } Java
@Take a look at void visualize_html_example() { var mannequin = new TodoList() .add("One") .add("Two") .addCompleted("Three"); var html = renderTemplate("/todo-list.tmpl", mannequin, "/"); assertThat(visualizeHtml(html)) .isEqualTo(normalizeWhitespace(""" ⬜ One ❌️ ⬜ Two ❌️ ✅ Three ❌️ """)); } Right here is Esko Luontola’s Java implementation of the 2 capabilities that make this potential, and my translation to Go of his code.
Go
func visualizeHtml(html string) string sturdy func normalizeWhitespace(s string) string { return strings.TrimSpace(replaceAll(s, "s+", " ")) } func replaceAll(src, regex, repl string) string { re := regexp.MustCompile(regex) return re.ReplaceAllString(src, repl) } supply
Java
public static String visualizeHtml(String html) i public static String normalizeWhitespace(String s) { return s.replaceAll("s+", " ").trim(); } supply
On this part, we have now seen a way for asserting HTML content material that’s an alternative choice to the CSS selector-based method utilized in the remainder of the article. Esko Luontola has reported nice success with it, and I hope readers have success with it too!
This system of asserting towards massive, difficult knowledge constructions similar to HTML pages by lowering them to a canonical string model has no identify that I do know of. Martin Fowler urged “stringly asserted”, and from his suggestion comes the identify of this part.
