Check Drive HTML Templates

Let’s have a look at methods to do it in phases: We begin with the next check that tries to compile the template. In Go we use the usual html/template package deal.

Go

  func Test_wellFormedHtml(t *testing.T) {
    templ := template.Should(template.ParseFiles("index.tmpl"))
    _ = templ
  }

In Java we use moustache
as a result of it is extremely straightforward to make use of; free marker both
Pace are different widespread choices.

Java

  @Check
  void indexIsSoundHtml() {
      var template = Mustache.compiler().compile(
              new InputStreamReader(
                      getClass().getResourceAsStream("/index.tmpl")));
  }

If we run this check, it should fail, as a result of the index.tmpl the file doesn’t exist. So we create it, with the damaged HTML above. Now the check ought to go.

Then we create a mannequin for the template to make use of. The app manages a to-do listing 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

  @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 byte 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 would like parse the HTML and we anticipate to see an error, as a result of in our damaged HTML there’s a div component that’s closed by a p component. There may be an HTML parser within the Go commonplace library, nevertheless it’s too forgiving: if we run it on our damaged HTML, we do not get an error. Luckily, the Go commonplace 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 could 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 carried out, it is legitimate!
      case nil:
        // do nothing
      default:
        t.Fatalf("Error parsing html: %s", err)
      }
    }
  }

fountain

This code configures the HTML parser to have the proper stage of leniency for HTML after which parses the HTML token by token. In actual fact, 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 component 

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();
  }

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And we see it fail:

java.lang.AssertionError: 
Anticipating empty however was:<(<1:13>: Sudden EndTag token () when in state (InBody),

Success! Now if we copy TodoMVC template content material to our index.tmpl file, the check passes.

The proof, nevertheless, is simply too detailed: we extract two auxiliary capabilities to make clear the intent of the proof and acquire

Go

  func Test_wellFormedHtml(t *testing.T) {
    mannequin := todo.NewList()
  
    buf := renderTemplate("index.tmpl", mannequin)
  
    assertWellFormedHtml(t, buf)
  }

fountain

Java

  @Check
  void indexIsSoundHtml() {
      var mannequin = new TodoList();
  
      var html = renderTemplate("/index.tmpl", mannequin);
  
      assertSoundHtml(html);
  }

fountain