We will as a substitute write unit assessments that use CSS selectors to probe the
presence and proper content material of particular HTML components inside a doc.
Parameterizing these assessments makes it straightforward so as to add new assessments and to obviously
point out what particulars every take a look at is verifying. This strategy works with any
language that has entry to an HTML parsing library that helps CSS
selectors; examples are supplied in Go and Java.
Stage 1: checking for sound HTML
The primary factor we need to test is that the HTML we produce is
mainly sound. I do not imply to test that HTML is legitimate based on the
W3C; it might be cool to do it, however it’s higher to start out with a lot easier and quicker checks.
As an illustration, we would like our assessments to
break if the template generates one thing like
<div>foo</p>
Let’s examine how one can 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 widespread decisions.
Java
@Check void indexIsSoundHtml() { var template = Mustache.compiler().compile( new InputStreamReader( getClass().getResourceAsStream("/index.tmpl"))); } If we run this take a look at, it’s 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 will 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
@Check 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
@Check 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 need to parse the HTML and we count on to see an
error, as a result of in our damaged HTML there’s a div ingredient that
is closed by a p ingredient. 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 (because of 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) } // test that the template will 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() change err { case io.EOF: return // We're performed, 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 wished:
--- FAIL: Test_wellFormedHtml (0.00s) index_template_test.go:61: Error parsing html: XML syntax error on line 4: sudden finish ingredient </p>
In Java, a flexible library to make use of is jsoup:
Java
@Check 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, nevertheless, is just 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
@Check 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 taking a look at how it’s rendered in a browser. Nonetheless, there may be usually
logic in templates, and we would like to have the ability to take a look at that logic.
One could be tempted to check the rendered HTML with string equality,
however this method fails in follow, as a result of templates include plenty of
particulars that make string equality assertions impractical. The assertions
develop 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 say that some components of the rendered HTML
correspond to what we count on, and to ignore all the main points we do not
care about. A method to do that is by operating 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 now we have
chosen these components, we (1) rely that the variety of ingredient returned
is what we count on, and (2) that they include the textual content or different content material
that we count on.
The UI that we’re alleged to generate seems like this:
There are a number of particulars which might be rendered dynamically:
- The variety of objects and their textual content content material change, clearly
- The type of the todo-item modifications when it is accomplished (e.g., the
second) - The “2 objects left” textual content will change with the variety of non-completed
objects - One of many three buttons “All”, “Energetic”, “Accomplished” might be
highlighted, relying on the present url; as an example if we resolve that the
url that exhibits solely the “Energetic” objects is /energetic, then when the present url
is /energetic, the “Energetic” button must 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 will 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, supplied for example:
index.tmpl
<part class="todoapp"> <ul class="todo-list"> <!-- These are right here simply to indicate the construction of the record objects --> <!-- Listing objects 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 must be `0 objects 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="#/energetic">Energetic</a> </li> <li> <a href="#/accomplished">Accomplished</a> </li> </ul> <!-- Hidden if no accomplished objects are left ↓ --> <button class="clear-completed">Clear accomplished</button> ⑤ </footer> </part>
supply
By wanting on the static model of the template, we will deduce which
CSS selectors can be utilized to determine the related components for the 5 dynamic
options listed above:
| characteristic | CSS selector |
| ① | All of the objects | ul.todo-list li |
| ② | Accomplished objects | ul.todo-list li.accomplished |
| ⓷ | Gadgets left | span.todo-count |
| ④ | Highlighted navigation hyperlink | ul.filters a.chosen |
| ⑤ | Clear accomplished button | button.clear-completed |
We will use these selectors to focus our assessments on simply the issues we need to take a look at.
Testing HTML content material
The primary take a look at will search for all of the objects, and show that the info
arrange by the take a look at is rendered appropriately.
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’d like a technique to question the HTML doc with our CSS selector; a great
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, particularly
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 { // Just a little 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
@Check 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 record from the
mannequin, this take a look at will fail, as a result of the static template
todo objects have completely different textual content:
Go
--- FAIL: Test_todoItemsAreShown (0.00s) index_template_test.go:44: First record merchandise: need Foo, bought Style JavaScript index_template_test.go:49: Second record merchandise: need Bar, bought 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 .Gadgets }} <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
Check each content material and soundness on the identical time
Our take a look at works, however it’s a bit verbose, particularly the Go model. If we will have extra
assessments, they’ll develop 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 must 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
@Check 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! Not less than for my part. Now that we extracted the parseHtml helper, it is
a good suggestion to test 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 will eliminate the primary take a look at that we wrote, as we at the moment are testing for sound HTML on a regular basis.
The second take a look at
Now we’re in a great place for testing extra rendering logic. The
second dynamic characteristic in our record is “Listing objects ought to get the category
accomplished when marked as accomplished”. We will 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
@Check 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 will be made inexperienced by including this little bit of logic to the
template:
Go
<ul class="todo-list"> {{ vary .Gadgets }} <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 will take a look at and add the varied dynamic options
that our template ought to have.
Make it straightforward so as to add new assessments
The primary of the 20 ideas from the superb speak by Russ Cox on Go
Testing is “Make it straightforward so as to add new take a look at circumstances“. Certainly, in Go there
is a bent to make most assessments parameterized, for this very purpose.
Alternatively, whereas Java has
good help
for parameterized assessments with JUnit 5, they aren’t used as a lot.
Since our present two assessments 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 will produce clear error messages when the take a look at
fails) - A mannequin (in our case a
todo.Listing) - A CSS selector
- An inventory of textual content matches that we anticipate finding after we run the CSS
selector on the rendered HTML.
So that is the info construction for our take a look at circumstances:
Go
var testCases = []struct { title string mannequin *todo.Listing selector string matches []string }{ { title: "all todo objects are proven", mannequin: todo.NewList(). Add("Foo"). Add("Bar"), selector: "ul.todo-list li", matches: []string{"Foo", "Bar"}, }, { title: "accomplished objects get the 'accomplished' class", mannequin: todo.NewList(). Add("Foo"). AddCompleted("Bar"), selector: "ul.todo-list li.accomplished", matches: []string{"Bar"}, }, } supply
Java
file TestCase(String title, TodoList mannequin, String selector, Listing<String> matches) { @Override public String toString() { return title; } } public static TestCase[] indexTestCases() { return new TestCase[]{ new TestCase( "all todo objects are proven", new TodoList() .add("Foo") .add("Bar"), "ul.todo-list li", Listing.of("Foo", "Bar")), new TestCase( "accomplished objects 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.title, 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), "sudden # 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.dimension()); for (int i = 0; i < take a look at.matches.dimension(); i++) { assertThat(choice.get(i).textual content()).isEqualTo(take a look at.matches.get(i)); } } supply
We will 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 objects are proven PASSED IndexTemplateTest > testIndexTemplate(TestCase) > [2] accomplished objects get the 'accomplished' class PASSED
Word how, by giving a reputation to our take a look at circumstances, we get very readable take a look at output, each on the terminal and within the IDE:
Having rewritten our two previous assessments in desk kind, it is now tremendous straightforward so as to add
one other. That is the take a look at for the “x objects left” textual content:
Go
{ title: "objects left", mannequin: todo.NewList(). Add("One"). Add("Two"). AddCompleted("Three"), selector: "span.todo-count", matches: []string{"2 objects left"}, }, supply
Java
new TestCase( "objects left", new TodoList() .add("One") .add("Two") .addCompleted("Three"), "span.todo-count", Listing.of("2 objects left")), supply
And the corresponding change within the html template is:
Go
<span class="todo-count"><sturdy>{{len .ActiveItems}}</sturdy> objects left</span> supply
Java – jmustache
<span class="todo-count"><sturdy>{{activeItemsCount}}</sturdy> objects 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 { Gadgets []*Merchandise } func (l *Listing) ActiveItems() []*Merchandise { var end result []*Merchandise for _, merchandise := vary l.Gadgets { if !merchandise.IsCompleted { end result = append(end result, merchandise) } } return end result } supply
Java
public class TodoList { personal closing Listing<TodoItem> objects = new ArrayList<>(); // ... public lengthy activeItemsCount() { return objects.stream().filter(TodoItem::isActive).rely(); } } supply
We have invested a little bit effort in our testing infrastructure, in order that including new
take a look at circumstances is simpler. Within the subsequent part, we’ll see that the necessities
for the following take a look at circumstances 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’ll 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 technique to discover out.
At the moment, all we cross to our template is our mannequin, which is a todo-list.
It isn’t appropriate so as to add the presently visited url to the mannequin, as a result of that’s
consumer navigation state, not software state.
So we have to cross extra data to the template past the mannequin. A straightforward approach
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 circumstances desk has yet another area:
Go
var testCases = []struct { title string mannequin *todo.Listing path string selector string matches []string }{ { title: "all todo objects are proven", mannequin: todo.NewList(). Add("Foo"). Add("Bar"), selector: "ul.todo-list li", matches: []string{"Foo", "Bar"}, }, // ... the opposite circumstances { title: "highlighted navigation hyperlink: All", path: "/", selector: "ul.filters a.chosen", matches: []string{"All"}, }, { title: "highlighted navigation hyperlink: Energetic", path: "/energetic", selector: "ul.filters a.chosen", matches: []string{"Energetic"}, }, { title: "highlighted navigation hyperlink: Accomplished", path: "/accomplished", selector: "ul.filters a.chosen", matches: []string{"Accomplished"}, }, } Java
file TestCase(String title, TodoList mannequin, String path, String selector, Listing<String> matches) { @Override public String toString() { return title; } } public static TestCase[] indexTestCases() { return new TestCase[]{ new TestCase( "all todo objects are proven", new TodoList() .add("Foo") .add("Bar"), "/", "ul.todo-list li", Listing.of("Foo", "Bar")), // ... the earlier circumstances new TestCase( "highlighted navigation hyperlink: All", new TodoList(), "/", "ul.filters a.chosen", Listing.of("All")), new TestCase( "highlighted navigation hyperlink: Energetic", new TodoList(), "/energetic", "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 circumstances, the mannequin is irrelevant;
whereas for the earlier circumstances, the trail is irrelevant. The Go syntax permits us
to initialize a struct with simply the fields we’re interested by, however Java doesn’t have
the same characteristic, so we’re pushed to cross further data, and this makes the take a look at circumstances
desk tougher to grasp.
A developer would possibly take a look at the primary take a look at case and marvel if the anticipated conduct relies upon
on the trail being set to "/", and could be tempted so as to add extra circumstances with
a distinct path. In the identical approach, when studying the
highlighted navigation hyperlink take a look at circumstances, the developer would possibly marvel if the
anticipated conduct depends upon the mannequin being set to an empty todo record. In that case, one would possibly
be led so as to add irrelevant take a look at circumstances for the highlighted hyperlink with non-empty todo-lists.
We need 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 approach: we will use
the builder sample,
popularized by Joshua Bloch.
We will rapidly write one for the Java TestCase file this fashion:
Java
file TestCase(String title, TodoList mannequin, String path, String selector, Listing<String> matches) { @Override public String toString() { return title; } public static closing class Builder { String title; TodoList mannequin; String path; String selector; Listing<String> matches; public Builder title(String title) { this.title = title; 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(title, mannequin, path, selector, matches); } } } Hand-coding builders is a little bit tedious, however doable, although there are
automated methods to write down them.
Now we will rewrite our Java take a look at circumstances with the Builder, to
obtain better readability:
Java
public static TestCase[] indexTestCases() { return new TestCase[]{ new TestCase.Builder() .title("all todo objects are proven") .mannequin(new TodoList() .add("Foo") .add("Bar")) .selector("ul.todo-list li") .matches("Foo", "Bar") .construct(), // ... different circumstances new TestCase.Builder() .title("highlighted navigation hyperlink: Accomplished") .path("/accomplished") .selector("ul.filters a.chosen") .matches("Accomplished") .construct(), }; } So, the place are we with our assessments? At current, they fail for the improper purpose: null-pointer exceptions
because of the lacking mannequin and path values.
So as to get our new take a look at circumstances to fail for the precise purpose, particularly 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 will 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.title, 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) // ... identical as earlier than }) } } supply
In Java, we will present default values within the builder:
Java
public static closing class Builder { String title; TodoList mannequin = new TodoList(); String path = "/"; String selector; Listing<String> matches; // ... } supply
With these modifications, we see that the final two take a look at circumstances, those for the highlighted hyperlink Energetic
and Accomplished fail, for the anticipated purpose 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 assessments cross, we make these modifications 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 "/energetic" }}chosen{{ finish }}" href="#/energetic">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="#/energetic">Energetic</a> </li> <li> <a class="{{ #pathCompleted }}chosen{{ /pathCompleted }}" href="#/accomplished">Accomplished</a> </li> </ul> supply
Because the Mustache template language doesn’t enable for equality testing, we should change the
knowledge handed to the template in order that we execute the equality assessments 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("/energetic"), "pathCompleted", path.equals("/accomplished") ); return template.execute(knowledge); } supply
And with these modifications, all of our assessments now cross.
To recap this part, we made the take a look at code a little bit bit extra sophisticated, in order that the take a look at
circumstances are clearer: this can be a excellent tradeoff!
Stage 3: testing HTML behaviour
Within the story to this point, we examined the behaviour of the HTML
templates, by checking the construction of the generated HTML.
That is good, however what if we wished to check the behaviour of the HTML
itself, plus any CSS and JavaScript it could use?
The behaviour of HTML by itself is often fairly apparent, as a result of
there may be 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 modifications fully when
we add CSS, that may disguise, present, transfer round issues and plenty extra, and
with JavaScript, that may add any behaviour to a web page.
In an software that’s primarily rendered server-side, we count on
that the majority 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 to this point, however what if we wished to hurry up the
software behaviour with a library equivalent to HTMX? This library works by way of particular
attributes which might be added to components so as to add Ajax behaviour. These
attributes are in impact a DSL that we would need 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 assessments;
can we use them for unitary assessments as a substitute? I believe that is doable,
utilizing the next strategies, though I have to admit I’ve but to attempt
this on an actual venture.
We’ll use the Playwright
library, that’s accessible for each Go and
Java. The assessments we
are going to write down might be slower, as a result of we must wait a couple of
seconds for the headless browser to start out, however will retain among the
essential traits of unit assessments, primarily that we’re testing
simply the HTML (and any related CSS and JavaScript), in isolation from
another server-side logic.
Persevering with with the TodoMVC
instance, the following factor we would need to take a look at is what occurs when the
consumer clicks on the checkbox of a todo merchandise. What we might prefer 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,
particularly the entire part with class “todoapp”, in order that we will present the
new state of the appliance together with the rely of remaining “energetic”
objects (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 may simply load the preliminary HTML. The take a look at
is a little bit 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 sudden requests panic("sudden 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("sudden 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(); } @Check void toggleTodoItem() { // Render the preliminary html TodoList mannequin = new TodoList() .add("One") .add("Two"); String initialHtml = renderTemplate("/index.tmpl", mannequin, "/"); attempt (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 sudden calls fail(String.format("Surprising request: %s %s", route.request().technique(), route.request().url())); } }); // load preliminary html web page.navigate("http://localhost:4567/index.html"); } } } supply
Initially of the take a look at, we initialize the mannequin with two todo
objects “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
attempt (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 supplies 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 would possibly 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 sudden requests panic("sudden 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 sudden calls fail(String.format("Surprising 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 at the moment are in a position to load arbitrary HTML in a
headless browser. Within the subsequent sections we’ll see how one can simulate consumer
interplay with components of the web page, and observe the web page’s
behaviour. However first we have to resolve an issue with the shortage of
identifiers in our area mannequin.
Figuring out todo objects
Now we need to click on on the “One” checkbox. The issue now we have is
that at current, now we have no technique to determine particular person todo objects, so
we introduce an Id area 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.Gadgets = append(l.Gadgets, &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.Gadgets = append(l.Gadgets, &merchandise) return l } func generateRandomId() int { return abs(rand.Int()) } Java – up to date mannequin with Id
public class TodoList { personal closing Listing<TodoItem> objects = new ArrayList<>(); public TodoList add(String title) { objects.add(new TodoItem(generateRandomId(), title, false)); return this; } public TodoList addCompleted(String title) { objects.add(new TodoItem(generateRandomId(), title, true)); return this; } public TodoList add(int id, String title) { objects.add(new TodoItem(id, title, false)); return this; } personal static int generateRandomId() { return new Random().nextInt(0, Integer.MAX_VALUE); } } public file 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 express 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
@Check void toggleTodoItem() { // Render the preliminary html TodoList mannequin = new TodoList() .add(101, "One") .add(102, "Two"); String initialHtml = renderTemplate("/index.tmpl", mannequin, "/"); } We at the moment are prepared to check consumer interplay with the web page.
Clicking on a todo merchandise
We need to simulate consumer interplay with the HTML web page. It could be
tempting to proceed to make use of CSS selectors to determine the precise
checkbox that we need to click on, however there’s a greater approach: there’s a
consensus amongst front-end builders that one of the best ways to check
interplay with a web page is to make use of it
the identical approach that customers do. As an illustration, you do not search for a
button by way of a CSS locator equivalent to button.purchase; as a substitute,
you search for one thing clickable with the label “Purchase”. In follow,
this implies figuring out components of the web page by way of 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{Identify: "One"}) if err := checkbox.Click on(); err != nil { t.Deadly(err) } } Java
@Check 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 bettering
accessibility of our generated HTML. Within the subsequent part, we are going to see
how one can 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 acquired, it ought to return some
stubbed HTML.
Go
} else if route.Request().URL() == "http://localhost:4567/toggle/101" && route.Request().Technique() == "POST" { // we count on {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 count on {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"), "software/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 accommodates a lot of the software is
reloaded.
Go
// click on on the "One" checkbox checkbox := web page.GetByRole(*playwright.AriaRoleCheckbox, playwright.PageGetByRoleOptions{Identify: "One"}) if err := checkbox.Click on(); err != nil { t.Deadly(err) } // test 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(); // test 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. So as 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 could 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 : "" ... Check: Test_toggleTodoItem Messages: <!DOCTYPE html><html lang="en"><head> <meta charset="utf-8"> <meta title="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 will 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 desired url. The data-hx-target tells HTMX
to repeat the HTML returned by the decision, to the ingredient 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 : "" ... Check: Test_toggleTodoItem Messages: <!DOCTYPE html><html lang="en"><head> <meta charset="utf-8"> <meta title="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 just isn’t there: now we have a part.todoapp nested
inside one other. Because of this we’re not utilizing the HTMX annotations
appropriately, and exhibits why this type of take a look at will be helpful. 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 ingredient. 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 how one can write a take a look at for the behaviour of our
HTML that, whereas utilizing the sophisticated 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
truth testing simply an HTML web page with any related CSS and JavaScript,
in isolation from different components of the appliance equivalent to controllers,
companies or repositories.
The take a look at prices 2-3 seconds of ready time for the headless browser to come back up, which is often an excessive amount of for a unit take a look at; nevertheless, like a unit take a look at, it is vitally steady, 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 writer of the net course tdd.mooc.fi, instructed an alternate to testing HTML with CSS selectors: the concept is to remodel 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, nevertheless, removes an excessive amount of of the HTML construction to be helpful. As an illustration, it doesn’t allow us to distinguish between energetic and accomplished objects. Some HTML ingredient symbolize seen content material: as an example
<enter worth="foo" />
exhibits a textual content field with the phrase “foo” that is a vital a part of the approach 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 instead of the ingredient when visualizing it for testing. With this,
<enter worth="foo" data-test-icon="[foo]" />
the enter ingredient 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 will assert in opposition to 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
@Check 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 doable, 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) em public static String normalizeWhitespace(String s) { return s.replaceAll("s+", " ").trim(); } supply
On this part, now we have seen a way for asserting HTML content material that’s a substitute for the CSS selector-based approach 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 in opposition to massive, sophisticated knowledge buildings equivalent to HTML pages by lowering them to a canonical string model has no title that I do know of. Martin Fowler instructed “stringly asserted”, and from his suggestion comes the title of this part.
