feat: add exact mode option for toHaveClass (#176)

README.md

@@ -46,6 +46,7 @@ clear to read and to maintain.
 <!-- START doctoc generated TOC please keep comment here to allow auto update -->
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 
+
 - [Installation](#installation)
 - [Usage](#usage)
 - [Custom matchers](#custom-matchers)
@@ -498,7 +499,7 @@ expect(button).toHaveAttribute('type', expect.not.stringContaining('but'))
 ### `toHaveClass`
 
 ```typescript
-toHaveClass(...classNames: string[])
+toHaveClass(...classNames: string[], options?: {exact: boolean})
 ```
 
 This allows you to check whether the given element has certain classes within
@@ -525,6 +526,9 @@ expect(deleteButton).toHaveClass('btn-danger btn')
 expect(deleteButton).toHaveClass('btn-danger', 'btn')
 expect(deleteButton).not.toHaveClass('btn-link')
 
+expect(deleteButton).toHaveClass('btn-danger extra btn', {exact: true}) // to check if the element has EXACTLY a set of classes
+expect(deleteButton).not.toHaveClass('btn-danger extra', {exact: true}) // if it has more than expected it is going to fail
+
 expect(noClasses).not.toHaveClass()
 ```
 
@@ -940,6 +944,7 @@ 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-class.js

@@ -2,21 +2,25 @@
 
 import {render} from './helpers/test-utils'
 
+const renderElementWithClasses = () =>
+  render(`
+<div>
+  <button data-testid="delete-button" class="btn extra btn-danger">
+    Delete item
+  </button>
+  <button data-testid="cancel-button">
+    Cancel
+  </button>
+  <svg data-testid="svg-spinner" class="spinner clockwise">
+    <path />
+  </svg>
+  <div data-testid="only-one-class" class="alone"></div>
+  <div data-testid="no-classes"></div>
+</div>
+`)
+
 test('.toHaveClass', () => {
-  const {queryByTestId} = render(`
-    <div>
-      <button data-testid="delete-button" class="btn extra btn-danger">
-        Delete item
-      </button>
-      <button data-testid="cancel-button">
-        Cancel
-      </button>
-      <svg data-testid="svg-spinner" class="spinner clockwise">
-        <path />
-      </svg>
-      <div data-testid="no-classes"></div>
-    </div>
-  `)
+  const {queryByTestId} = renderElementWithClasses()
 
   expect(queryByTestId('delete-button')).toHaveClass('btn')
   expect(queryByTestId('delete-button')).toHaveClass('btn-danger')
@@ -91,3 +95,89 @@ test('.toHaveClass', () => {
     expect(queryByTestId('delete-button')).not.toHaveClass('  '),
   ).toThrowError(/(none)/)
 })
+
+test('.toHaveClass with exact mode option', () => {
+  const {queryByTestId} = renderElementWithClasses()
+
+  expect(queryByTestId('delete-button')).toHaveClass('btn extra btn-danger', {
+    exact: true,
+  })
+  expect(queryByTestId('delete-button')).not.toHaveClass('btn extra', {
+    exact: true,
+  })
+  expect(
+    queryByTestId('delete-button'),
+  ).not.toHaveClass('btn extra btn-danger foo', {exact: true})
+
+  expect(queryByTestId('delete-button')).toHaveClass('btn extra btn-danger', {
+    exact: false,
+  })
+  expect(queryByTestId('delete-button')).toHaveClass('btn extra', {
+    exact: false,
+  })
+  expect(
+    queryByTestId('delete-button'),
+  ).not.toHaveClass('btn extra btn-danger foo', {exact: false})
+
+  expect(queryByTestId('delete-button')).toHaveClass(
+    'btn',
+    'extra',
+    'btn-danger',
+    {exact: true},
+  )
+  expect(queryByTestId('delete-button')).not.toHaveClass('btn', 'extra', {
+    exact: true,
+  })
+  expect(queryByTestId('delete-button')).not.toHaveClass(
+    'btn',
+    'extra',
+    'btn-danger',
+    'foo',
+    {exact: true},
+  )
+
+  expect(queryByTestId('delete-button')).toHaveClass(
+    'btn',
+    'extra',
+    'btn-danger',
+    {exact: false},
+  )
+  expect(queryByTestId('delete-button')).toHaveClass('btn', 'extra', {
+    exact: false,
+  })
+  expect(queryByTestId('delete-button')).not.toHaveClass(
+    'btn',
+    'extra',
+    'btn-danger',
+    'foo',
+    {exact: false},
+  )
+
+  expect(queryByTestId('only-one-class')).toHaveClass('alone', {exact: true})
+  expect(queryByTestId('only-one-class')).not.toHaveClass('alone foo', {
+    exact: true,
+  })
+  expect(queryByTestId('only-one-class')).not.toHaveClass('alone', 'foo', {
+    exact: true,
+  })
+
+  expect(queryByTestId('only-one-class')).toHaveClass('alone', {exact: false})
+  expect(queryByTestId('only-one-class')).not.toHaveClass('alone foo', {
+    exact: false,
+  })
+  expect(queryByTestId('only-one-class')).not.toHaveClass('alone', 'foo', {
+    exact: false,
+  })
+
+  expect(() =>
+    expect(queryByTestId('only-one-class')).not.toHaveClass('alone', {
+      exact: true,
+    }),
+  ).toThrowError(/Expected the element not to have EXACTLY defined classes/)
+
+  expect(() =>
+    expect(queryByTestId('only-one-class')).toHaveClass('alone', 'foo', {
+      exact: true,
+    }),
+  ).toThrowError(/Expected the element to have EXACTLY defined classes/)
+})

src/to-have-class.js

@@ -1,6 +1,20 @@
 import {matcherHint, printExpected} from 'jest-matcher-utils'
 import {checkHtmlElement, getMessage} from './utils'
 
+function getExpectedClassNamesAndOptions(params) {
+  const lastParam = params.pop()
+  let expectedClassNames, options
+
+  if (typeof lastParam === 'object') {
+    expectedClassNames = params
+    options = lastParam
+  } else {
+    expectedClassNames = params.concat(lastParam)
+    options = {}
+  }
+  return {expectedClassNames, options}
+}
+
 function splitClassNames(str) {
   if (!str) {
     return []
@@ -12,13 +26,31 @@ function isSubset(subset, superset) {
   return subset.every(item => superset.includes(item))
 }
 
-export function toHaveClass(htmlElement, ...expectedClassNames) {
+export function toHaveClass(htmlElement, ...params) {
   checkHtmlElement(htmlElement, toHaveClass, this)
+  const {expectedClassNames, options} = getExpectedClassNamesAndOptions(params)
+
   const received = splitClassNames(htmlElement.getAttribute('class'))
   const expected = expectedClassNames.reduce(
     (acc, className) => acc.concat(splitClassNames(className)),
     [],
   )
+
+  if (options.exact) {
+    return {
+      pass: isSubset(expected, received) && expected.length === received.length,
+      message: () => {
+        const to = this.isNot ? 'not to' : 'to'
+        return getMessage(
+          `Expected the element ${to} have EXACTLY defined classes`,
+          expected.join(' '),
+          'Received',
+          received.join(' '),
+        )
+      },
+    }
+  }
+
   return expected.length > 0
     ? {
         pass: isSubset(expected, received),