test: add types test for classes parameter (#945)

Author: 38elements

Diff for: docs/guides/testing-single-file-components-with-jest.md

@@ -1,4 +1,4 @@
-## Testing Single File Components with Jest
+## Testing Single-File Components with Jest
 
 > An example project for this setup is available on [GitHub](https://github.com/vuejs/vue-test-utils-jest-example).
 

Diff for: docs/guides/testing-single-file-components-with-karma.md

@@ -1,4 +1,4 @@
-## Testing Single File Components with Karma
+## Testing Single-File Components with Karma
 
 > An example project for this setup is available on [GitHub](https://github.com/eddyerburgh/vue-test-utils-karma-example).
 

Diff for: docs/guides/testing-single-file-components-with-mocha-webpack.md

@@ -1,4 +1,4 @@
-## Testing Single File Components with Mocha + webpack
+## Testing Single-File Components with Mocha + webpack
 
 > An example project for this setup is available on [GitHub](https://github.com/vuejs/vue-test-utils-mocha-webpack-example).
 

Diff for: packages/test-utils/types/test/wrapper.ts

@@ -19,6 +19,7 @@ bool = wrapper.hasClass('foo-class')
 bool = wrapper.hasProp('checked', true)
 bool = wrapper.props().checked
 bool = wrapper.hasStyle('color', 'red')
+bool = wrapper.classes('foo')
 
 bool = wrapper.is(normalOptions)
 bool = wrapper.isEmpty()
@@ -66,10 +67,12 @@ wrapper.setChecked()
 wrapper.setChecked(true)
 wrapper.setValue('some string')
 wrapper.setSelected()
+wrapper.props('foo')
 
 let str: string = wrapper.html()
 str = wrapper.text()
 str = wrapper.name()
+wrapper.attributes('foo')
 
 /**
  * Tests for WrapperArray API