feat: remove deprecation when is is called with component definition (#1676)

Author: xanf

docs/api/wrapper/is.md

@@ -1,17 +1,19 @@
 ## is
 
 ::: warning Deprecation warning
-Using `is` to assert that DOM node or `vm` matches selector is deprecated and will be removed.
+Using `is` to assert that wrapper matches DOM selector is deprecated and will be removed.
 
-Consider a custom matcher such as those provided in [jest-dom](https://github.com/testing-library/jest-dom#custom-matchers).
+For such use cases consider a custom matcher such as those provided in [jest-dom](https://github.com/testing-library/jest-dom#custom-matchers).
 or for DOM element type assertion use native [`Element.tagName`](https://developer.mozilla.org/en-US/docs/Web/API/Element/tagName) instead.
 
 To keep these tests, a valid replacement for:
 
-- `is('DOM_SELECTOR')` is a assertion of `wrapper.element.tagName`.
+- `is('DOM_SELECTOR')` is an assertion of `wrapper.element.tagName`.
 - `is('ATTR_NAME')` is a truthy assertion of `wrapper.attributes('ATTR_NAME')`.
 - `is('CLASS_NAME')` is a truthy assertion of `wrapper.classes('CLASS_NAME')`.
 
+Assertion against component definition is not deprecated
+
 When using with findComponent, access the DOM element with `findComponent(Comp).element`
 :::
 

packages/test-utils/src/wrapper.js

@@ -321,13 +321,18 @@ export default class Wrapper implements BaseWrapper {
   }
 
   /**
-   * Checks if node matches selector
-   * @deprecated
+   * Checks if node matches selector or component definition
    */
   is(rawSelector: Selector): boolean {
-    warnDeprecated('is', 'Use element.tagName instead')
     const selector = getSelector(rawSelector, 'is')
 
+    if (selector.type === DOM_SELECTOR) {
+      warnDeprecated(
+        'checking tag name with `is`',
+        'Use `element.tagName` instead'
+      )
+    }
+
     if (selector.type === REF_SELECTOR) {
       throwError('$ref selectors can not be used with wrapper.is()')
     }

test/specs/wrapper/is.spec.js

@@ -1,4 +1,5 @@
 import { compileToFunctions } from 'vue-template-compiler'
+import { config } from 'packages/test-utils/src'
 import ComponentWithChild from '~resources/components/component-with-child.vue'
 import Component from '~resources/components/component.vue'
 import ComponentWithoutName from '~resources/components/component-without-name.vue'
@@ -10,6 +11,17 @@ import {
 } from '~resources/utils'
 
 describeWithShallowAndMount('is', mountingMethod => {
+  let consoleErrorSave
+
+  beforeEach(() => {
+    consoleErrorSave = console.error
+    console.error = jest.fn()
+  })
+
+  afterEach(() => {
+    console.error = consoleErrorSave
+  })
+
   it('returns true if root node matches tag selector', () => {
     const compiled = compileToFunctions('<input />')
     const wrapper = mountingMethod(compiled)
@@ -133,4 +145,25 @@ describeWithShallowAndMount('is', mountingMethod => {
       expect(fn).toThrow(message)
     })
   })
+
+  it('warns when passing a string', () => {
+    const wrapper = mountingMethod(Component)
+
+    config.showDeprecationWarnings = true
+    wrapper.is('div')
+
+    expect(console.error.mock.calls[0][0]).toContain(
+      '[vue-test-utils]: checking tag name with `is` is deprecated'
+    )
+    config.showDeprecationWarnings = false
+  })
+
+  it('does not warn when passing a component definition', () => {
+    const wrapper = mountingMethod(Component)
+
+    config.showDeprecationWarnings = true
+    wrapper.is(Component)
+
+    expect(console.error).not.toHaveBeenCalled()
+  })
 })