feat: Add toHaveDisplayValue() matcher (#223)

* Introduce .toHaveDisplay() custom matcher
* Improve docs by showing getByLabelText usage
* Apply suggestions from code review
* Add input and textarea examples to readme
* Add support for input and textarea elements
* Update README.md
* Update docs description to match the new elements supported
* Add value change expects for input, select and textarea

Co-authored-by: Toni Villena <[email protected]>
Co-authored-by: Ernesto García <[email protected]>

Author: 3 people

README.md

@@ -66,6 +66,7 @@ clear to read and to maintain.
   - [`toHaveStyle`](#tohavestyle)
   - [`toHaveTextContent`](#tohavetextcontent)
   - [`toHaveValue`](#tohavevalue)
+  - [`toHaveDisplayValue`](#tohavedisplayvalue)
   - [`toBeChecked`](#tobechecked)
 - [Deprecated matchers](#deprecated-matchers)
   - [`toBeInTheDOM`](#tobeinthedom)
@@ -732,8 +733,8 @@ toHaveValue(value: string | string[] | number)
 
 This allows you to check whether the given form element has the specified value.
 It accepts `<input>`, `<select>` and `<textarea>` elements with the exception of
-of `<input type="checkbox">` and `<input type="radio">`, which can be
-meaningfully matched only using [`toBeChecked`](#tobechecked) or
+`<input type="checkbox">` and `<input type="radio">`, which can be meaningfully
+matched only using [`toBeChecked`](#tobechecked) or
 [`toHaveFormValues`](#tohaveformvalues).
 
 For all other form elements, the value is matched using the same algorithm as in
@@ -768,6 +769,61 @@ expect(selectInput).not.toHaveValue(['second', 'third'])
 
 <hr />
 
+### `toHaveDisplayValue`
+
+```typescript
+toHaveDisplayValue(value: string | string[])
+```
+
+This allows you to check whether the given form element has the specified
+displayed value (the one the end user will see). It accepts `<input>`,
+`<select>` and `<textarea>` elements with the exception of
+`<input type="checkbox">` and `<input type="radio">`, which can be meaningfully
+matched only using [`toBeChecked`](#tobechecked) or
+[`toHaveFormValues`](#tohaveformvalues).
+
+#### Examples
+
+```html
+<label for="input-example">First name</label>
+<input type="text" id="input-example" value="Luca" />
+
+<label for="textarea-example">Description</label>
+<textarea id="textarea-example">An example description here.</textarea>
+
+<label for="single-select-example">Fruit</label>
+<select id="single-select-example">
+  <option value="">Select a fruit...</option>
+  <option value="banana">Banana</option>
+  <option value="ananas">Ananas</option>
+  <option value="avocado">Avocado</option>
+</select>
+
+<label for="mutiple-select-example">Fruits</label>
+<select id="multiple-select-example" multiple>
+  <option value="">Select a fruit...</option>
+  <option value="banana" selected>Banana</option>
+  <option value="ananas">Ananas</option>
+  <option value="avocado" selected>Avocado</option>
+</select>
+```
+
+##### Using DOM Testing Library
+
+```javascript
+const input = screen.getByLabelText('First name')
+const textarea = screen.getByLabelText('Description')
+const selectSingle = screen.getByLabelText('Fruit')
+const selectMultiple = screen.getByLabelText('Fruits')
+
+expect(input).toHaveDisplayValue('Luca')
+expect(textarea).toHaveDisplayValue('An example description here.')
+expect(selectSingle).toHaveDisplayValue('Select a fruit...')
+expect(selectMultiple).toHaveDisplayValue(['Banana', 'Avocado'])
+```
+
+<hr />
+
 ### `toBeChecked`
 
 ```typescript
@@ -959,6 +1015,7 @@ Thanks goes to these people ([emoji key][emojis]):
 
 <!-- markdownlint-enable -->
 <!-- prettier-ignore-end -->
+
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors][all-contributors] specification.

src/__tests__/to-have-display-value.js

@@ -0,0 +1,119 @@
+import {render} from './helpers/test-utils'
+
+test('it should work as expected', () => {
+  const {queryByTestId} = render(`
+    <select id="fruits" data-testid="select">
+      <option value="">Select a fruit...</option>
+      <option value="ananas">Ananas</option>
+      <option value="banana">Banana</option>
+      <option value="avocado">Avocado</option>
+    </select>
+  `)
+
+  expect(queryByTestId('select')).toHaveDisplayValue('Select a fruit...')
+  expect(queryByTestId('select')).not.toHaveDisplayValue('Banana')
+  expect(() =>
+    expect(queryByTestId('select')).not.toHaveDisplayValue('Select a fruit...'),
+  ).toThrow()
+  expect(() =>
+    expect(queryByTestId('select')).toHaveDisplayValue('Ananas'),
+  ).toThrow()
+
+  queryByTestId('select').value = 'banana'
+  expect(queryByTestId('select')).toHaveDisplayValue('Banana')
+})
+
+test('it should work with select multiple', () => {
+  const {queryByTestId} = render(`
+    <select id="fruits" data-testid="select" multiple>
+      <option value="">Select a fruit...</option>
+      <option value="ananas" selected>Ananas</option>
+      <option value="banana">Banana</option>
+      <option value="avocado" selected>Avocado</option>
+    </select>
+  `)
+
+  expect(queryByTestId('select')).toHaveDisplayValue(['Ananas', 'Avocado'])
+  expect(() =>
+    expect(queryByTestId('select')).not.toHaveDisplayValue([
+      'Ananas',
+      'Avocado',
+    ]),
+  ).toThrow()
+
+  expect(queryByTestId('select')).not.toHaveDisplayValue('Ananas')
+  expect(() =>
+    expect(queryByTestId('select')).toHaveDisplayValue('Ananas'),
+  ).toThrow()
+
+  Array.from(queryByTestId('select').options).forEach(option => {
+    option.selected = ['ananas', 'banana'].includes(option.value)
+  })
+
+  expect(queryByTestId('select')).toHaveDisplayValue(['Ananas', 'Banana'])
+})
+
+test('it should work with input elements', () => {
+  const {queryByTestId} = render(`
+    <input type="text" data-testid="input" value="Luca" />
+  `)
+
+  expect(queryByTestId('input')).toHaveDisplayValue('Luca')
+
+  queryByTestId('input').value = 'Piero'
+  expect(queryByTestId('input')).toHaveDisplayValue('Piero')
+})
+
+test('it should work with textarea elements', () => {
+  const {queryByTestId} = render(
+    '<textarea data-testid="textarea-example">An example description here.</textarea>',
+  )
+
+  expect(queryByTestId('textarea-example')).toHaveDisplayValue(
+    'An example description here.',
+  )
+
+  queryByTestId('textarea-example').value = 'Another example'
+  expect(queryByTestId('textarea-example')).toHaveDisplayValue(
+    'Another example',
+  )
+})
+
+test('it should throw if element is not valid', () => {
+  const {queryByTestId} = render(`
+    <div data-testid="div">Banana</div>
+    <input type="radio" data-testid="radio" value="Something" />
+    <input type="checkbox" data-testid="checkbox" />
+  `)
+
+  let errorMessage
+  try {
+    expect(queryByTestId('div')).toHaveDisplayValue('Banana')
+  } catch (err) {
+    errorMessage = err.message
+  }
+
+  expect(errorMessage).toMatchInlineSnapshot(
+    `".toHaveDisplayValue() currently supports only input, textarea or select elements, try with another matcher instead."`,
+  )
+
+  try {
+    expect(queryByTestId('radio')).toHaveDisplayValue('Something')
+  } catch (err) {
+    errorMessage = err.message
+  }
+
+  expect(errorMessage).toMatchInlineSnapshot(
+    `".toHaveDisplayValue() currently does not support input[type=\\"radio\\"], try with another matcher instead."`,
+  )
+
+  try {
+    expect(queryByTestId('checkbox')).toHaveDisplayValue(true)
+  } catch (err) {
+    errorMessage = err.message
+  }
+
+  expect(errorMessage).toMatchInlineSnapshot(
+    `".toHaveDisplayValue() currently does not support input[type=\\"checkbox\\"], try with another matcher instead."`,
+  )
+})

src/matchers.js

@@ -14,6 +14,7 @@ import {toBeDisabled, toBeEnabled} from './to-be-disabled'
 import {toBeRequired} from './to-be-required'
 import {toBeInvalid, toBeValid} from './to-be-invalid'
 import {toHaveValue} from './to-have-value'
+import {toHaveDisplayValue} from './to-have-display-value'
 import {toBeChecked} from './to-be-checked'
 
 export {
@@ -35,5 +36,6 @@ export {
   toBeInvalid,
   toBeValid,
   toHaveValue,
+  toHaveDisplayValue,
   toBeChecked,
 }

src/to-have-display-value.js

@@ -0,0 +1,44 @@
+import {matcherHint} from 'jest-matcher-utils'
+
+import {checkHtmlElement, getMessage} from './utils'
+
+export function toHaveDisplayValue(htmlElement, expectedValue) {
+  checkHtmlElement(htmlElement, toHaveDisplayValue, this)
+  const tagName = htmlElement.tagName.toLowerCase()
+
+  if (!['select', 'input', 'textarea'].includes(tagName)) {
+    throw new Error(
+      '.toHaveDisplayValue() currently supports only input, textarea or select elements, try with another matcher instead.',
+    )
+  }
+
+  if (tagName === 'input' && ['radio', 'checkbox'].includes(htmlElement.type)) {
+    throw new Error(
+      `.toHaveDisplayValue() currently does not support input[type="${htmlElement.type}"], try with another matcher instead.`,
+    )
+  }
+
+  const value =
+    tagName === 'select'
+      ? Array.from(htmlElement)
+          .filter(option => option.selected)
+          .map(option => option.textContent)
+          .toString()
+      : htmlElement.value
+
+  return {
+    pass: value === expectedValue.toString(),
+    message: () =>
+      getMessage(
+        matcherHint(
+          `${this.isNot ? '.not' : ''}.toHaveDisplayValue`,
+          'element',
+          '',
+        ),
+        `Expected element ${this.isNot ? 'not ' : ''}to have display value`,
+        expectedValue,
+        'Received',
+        value,
+      ),
+  }
+}