Implement Ember semantics for {{#if}}/{{#unless}}

[chancancode]

Also ported most of the basic test cases to the new format. I expect the super classes here can be extracted into a different file and we should be able to reuse all the test cases for the inline (if …) and (unless …) helpers as well, because of the test cases go through the templateFor abstraction.

I have not figured out a good way to abstract the “without inverse” tests, so they are duplicated in the leaf subclasses.

The rest of the tests in the if_unless_test requires some more careful reading/git-history-digging to see if they are still relevant, which I do not have time for at the moment (maybe someone else can pick up where I left off).

In any case, implementing the Ember semantics should be enough to unblock porting other tests that depends on them. I did not implement the inline (if …) and (unless …) helpers or port their tests, but that should be pretty easy given the {{concat}} example and the toBool function in here.

Note: please don’t add the inline (if …) and (unless …) tests here. Instead, please add them to integration/helpers/if-unless-test.js (and extract the shared test cases to a different file too).

cc @wycats @rwjblue @mmun @Serabe

[chancancode]

For the inline helpers, we can potentially subclass multiple times for test the same helpers in different positions. Something like:

moduleFor('Helpers test: {{if}} used in content position', class extends SharedConditionalsTest {

  wrapperFor(templates) {
    return templates.join('');
  }

  templateFor({ cond, truthy, falsy }) {
    return `{{if ${cond} "${truthy}" "${falsy}"}}`;
  }

  get result() {
    jQuery(this.element).text();
  }

});

moduleFor('Helpers test: {{if}} used with another helper', class extends SharedConditionalsTest {

  wrapperFor(templates) {
    return `{{concat ${templates.join(' ')}}}`;
  }

  templateFor({ cond, truthy, falsy }) {
    return `(if ${cond} "${truthy}" "${falsy}")`;
  }

  get result() {
    jQuery(this.element).text();
  }

});

moduleFor('Helpers test: {{if}} used in attribute position', class extends SharedConditionalsTest {

  wrapperFor(templates) {
    return `<div data-foo="${templates.join('')}" />`;
  }

  templateFor({ cond, truthy, falsy }) {
    return `{{if ${cond} "${truthy}" "${falsy}"}}`;
  }

  get result() {
    jQuery('div', this.element).data('foo');
  }

});

[chancancode]

This comment should probably be moved up.

[chancancode]

Replaced by:

• "it tests for isTruthy if available"
• "it tests for isTruthy on Ember objects if available"

(Now testing re-render, mutation and replacement as well)

[chancancode]

I think this is good to merge regardless of how we feel about my comments – if we feel that we are missing any coverage I am happy to revert removing those particular tests (keeping them in the old tests) and come back to it another day.

[chancancode]

After merging this, we should unskip https://github.com/emberjs/ember.js/pull/12910/files#diff-143647b81033de48d2908310dcce5644R46 for glimmer once we implemented user helpers lookup.

[rwjblue]

Thanks for the extra comments. Made review much easier.