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fix: normalize expected value in toContainHTML #349

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merged 1 commit into from Mar 25, 2021
Merged

fix: normalize expected value in toContainHTML #349

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20 changes: 12 additions & 8 deletions src/__tests__/to-contain-html.js
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Expand Up @@ -18,21 +18,22 @@ describe('.toContainHTML', () => {
const nonExistantElement = queryByTestId('not-exists')
const fakeElement = {thisIsNot: 'an html element'}
const stringChildElement = '<span data-testid="child"></span>'
const stringChildElementSelfClosing = '<span data-testid="child" />'
const incorrectStringHtml = '<span data-testid="child"></div>'
const nonExistantString = '<span> Does not exists </span>'
const svgElement = queryByTestId('svg-element')

expect(grandparent).toContainHTML(stringChildElement)
expect(parent).toContainHTML(stringChildElement)
expect(child).toContainHTML(stringChildElement)
expect(child).toContainHTML(stringChildElementSelfClosing)
expect(grandparent).not.toContainHTML(nonExistantString)
expect(parent).not.toContainHTML(nonExistantString)
expect(child).not.toContainHTML(nonExistantString)
expect(child).not.toContainHTML(nonExistantString)
expect(grandparent).not.toContainHTML(incorrectStringHtml)
expect(parent).not.toContainHTML(incorrectStringHtml)
expect(child).not.toContainHTML(incorrectStringHtml)
expect(child).not.toContainHTML(incorrectStringHtml)
Comment on lines -32 to -35
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Do we need to remove the test on the invalid html? What happens after these changes if we give invalid html like the one in this string? It'd be nice to know and add a test for that. And hopefully that what it does is still close to what one would expect.

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I agree, the tests can stay, just need to flip the direction, as this assertion now passes.

Fixed in the next revision

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How is it that these tests now pass? I would expect them not to pass. The rendered DOM in this test does contain the invalid html given. 🤔

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HTML parser ignores unmatching closing tags. Currently we have this content: <span data-testid="child"></div>. After normalization via innerHTML it becomes <span data-testid="child"></span> and this matches the actual content.

With normalization, this test will not pass, for example:

const {container} = render(`<table>
  <tr>
    <td>test</td>
  </tr>
</table>`)
expect(container).toContainHTML('<table>test</table>');

<table>test</table> does not expand to the full table and does not match the real content

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Hmmm, I wonder if we could detect that, and disallow invalid html. This also makes it technically a breaking change, although I'm thinking that I'll pass on that, since it is very unlikely someone was passing invalid html to explicitly expect a failure.

I think this is good to go. Will merge soon.

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I am not sure this is possible without rolling your own parser. Built-in DOM parser does not expose enough information.

I am also wondering about the use-case here. Spotting the typos is nice, but is there any more important case where it is needed?

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Not really, which is why I said I approve anyway. It's just a bit unintuitive, but I agree that it makes sense since it is how html works anyway. Developing our own parser is out of the question. This matcher is anyway an outlier, in the sense that we do not recommed its use except in some unique circumstances.

expect(grandparent).toContainHTML(incorrectStringHtml)
expect(parent).toContainHTML(incorrectStringHtml)
expect(child).toContainHTML(incorrectStringHtml)

// negative test cases wrapped in throwError assertions for coverage.
expect(() =>
Expand All @@ -59,6 +60,9 @@ describe('.toContainHTML', () => {
expect(() =>
expect(child).not.toContainHTML(stringChildElement),
).toThrowError()
expect(() =>
expect(child).not.toContainHTML(stringChildElementSelfClosing),
).toThrowError()
expect(() => expect(child).toContainHTML(nonExistantString)).toThrowError()
expect(() => expect(parent).toContainHTML(nonExistantString)).toThrowError()
expect(() =>
Expand All @@ -72,16 +76,16 @@ describe('.toContainHTML', () => {
expect(grandparent).toContainHTML(nonExistantElement),
).toThrowError()
expect(() =>
expect(nonExistantElement).toContainHTML(incorrectStringHtml),
expect(nonExistantElement).not.toContainHTML(incorrectStringHtml),
).toThrowError()
expect(() =>
expect(grandparent).toContainHTML(incorrectStringHtml),
expect(grandparent).not.toContainHTML(incorrectStringHtml),
).toThrowError()
expect(() =>
expect(child).toContainHTML(incorrectStringHtml),
expect(child).not.toContainHTML(incorrectStringHtml),
).toThrowError()
expect(() =>
expect(parent).toContainHTML(incorrectStringHtml),
expect(parent).not.toContainHTML(incorrectStringHtml),
).toThrowError()
})

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12 changes: 11 additions & 1 deletion src/to-contain-html.js
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@@ -1,10 +1,20 @@
import {checkHtmlElement} from './utils'

function getNormalizedHtml(container, htmlText) {
const div = container.ownerDocument.createElement('div')
div.innerHTML = htmlText
return div.innerHTML
}

export function toContainHTML(container, htmlText) {
checkHtmlElement(container, toContainHTML, this)

if (typeof htmlText !== 'string') {
throw new Error(`.toContainHTML() expects a string value, got ${htmlText}`)
}
Comment on lines +12 to +14
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Without this change, the nonExistantElement tests started failing. This value is basically an equivalent of expect(element).toContainHTML(null) which turned into a string.includes(null), producing false.

Now the htmlText always gets converted to a string, so this extra check is needed to keep the assertions failing where they were before.


return {
pass: container.outerHTML.includes(htmlText),
pass: container.outerHTML.includes(getNormalizedHtml(container, htmlText)),
message: () => {
return [
this.utils.matcherHint(
Expand Down