feat(rules): added rule for prefer-to-have-class (#118)

* feat(rules): added rule prefer-to-have-class

* more tests

* fixed typeo

* covg

* Apply suggestions from code review

Co-authored-by: Anton Niklasson <[email protected]>

* classList

Co-authored-by: Anton Niklasson <[email protected]>

Author: benmonro

README.md

@@ -110,6 +110,7 @@ module.exports = {
 | [prefer-in-document](https://github.com/testing-library/eslint-plugin-jest-dom/blob/master/docs/rules/prefer-in-document.md)                   | 👍  | 🔧  | Prefer .toBeInTheDocument() for asserting the existence of a DOM node |
 | [prefer-required](https://github.com/testing-library/eslint-plugin-jest-dom/blob/master/docs/rules/prefer-required.md)                         | 👍  | 🔧  | prefer toBeRequired over checking properties                          |
 | [prefer-to-have-attribute](https://github.com/testing-library/eslint-plugin-jest-dom/blob/master/docs/rules/prefer-to-have-attribute.md)       | 👍  | 🔧  | prefer toHaveAttribute over checking getAttribute/hasAttribute        |
+| [prefer-to-have-class](https://github.com/testing-library/eslint-plugin-jest-dom/blob/master/docs/rules/prefer-to-have-class.md)               | 👍  | 🔧  | prefer toHaveClass over checking element className                    |
 | [prefer-to-have-style](https://github.com/testing-library/eslint-plugin-jest-dom/blob/master/docs/rules/prefer-to-have-style.md)               | 👍  | 🔧  | prefer toHaveStyle over checking element style                        |
 | [prefer-to-have-text-content](https://github.com/testing-library/eslint-plugin-jest-dom/blob/master/docs/rules/prefer-to-have-text-content.md) | 👍  | 🔧  | Prefer toHaveTextContent over checking element.textContent            |
 | [prefer-to-have-value](https://github.com/testing-library/eslint-plugin-jest-dom/blob/master/docs/rules/prefer-to-have-value.md)               | 👍  | 🔧  | prefer toHaveValue over checking element.value                        |

docs/rules/prefer-to-have-class.md

@@ -0,0 +1,40 @@
+# prefer toHaveClass over checking element.class (prefer-to-have-class)
+
+This rule is an autofixable rule that reports usages of checking element className or classList in expect statements in preference of using the jest-dom
+`toHaveClass` matcher.
+
+## Rule Details
+
+Examples of **incorrect** code for this rule:
+
+```js
+expect(el.className).toBe("bar");
+expect(el.className).not.toBe("bar");
+expect(el.className).toHaveProperty("class", "foo");
+expect(screen.getByTestId("foo").className).toBe("foo");
+expect(el.className).toContain("bar");
+expect(el.className).not.toContain("baz");
+expect(el).toHaveAttribute("class", "qux");
+
+expect(el.classList[0]).toBe("foo");
+expect(el.classList[0]).toBe("bar");
+```
+
+Examples of **correct** code for this rule:
+
+```js
+expect(el).toHaveClass("bar");
+expect(el).toHaveStyle({ foo: "bar" });
+expect(el.class).toMatchSnapshot();
+expect(el.class).toEqual(foo);
+```
+
+## When Not To Use It
+
+If you don't care about using built in matchers for checking class on dom
+elements.
+
+## Further Reading
+
+- [jest-dom toHaveStyle](https://github.com/testing-library/jest-dom#tohaveclass)
+- [ElementCSSInlineStyle.class](https://developer.mozilla.org/en-US/docs/Web/API/ElementCSSInlineStyle/class)

docs/rules/prefer-to-have-style.md

@@ -1,4 +1,4 @@
-# prefer toHaveProperty over checking element.style (prefer-to-have-style)
+# prefer toHaveStyle over checking element.style (prefer-to-have-style)
 
 This rule is an autofixable rule that reports usages of checking element.style in expect statements in preference of using the jest-dom
 `toHaveStyle` matcher.

src/__tests__/lib/rules/prefer-prefer-to-have-class.js

@@ -0,0 +1,137 @@
+import { RuleTester } from "eslint";
+import * as rule from "../../../rules/prefer-to-have-class";
+
+const errors = [{ messageId: "use-to-have-class" }];
+const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 2015 } });
+ruleTester.run("prefer-to-have-class", rule, {
+  valid: [
+    `expect(el).toHaveClass("bar")`,
+    `expect(el.class).toEqual(foo)`,
+    `expect(el).toHaveAttribute("class")`,
+    `expect(el).toHaveAttribute("className", "bar")`,
+    `expect(el).toHaveAttribute("clazz", "bar")`,
+    `expect(el).not.toHaveAttribute("clazz", "bar")`,
+    `expect(el).not.toHaveAttribute("clazz", expect.stringContaining("bar"))`,
+    `expect(el).toHaveAttribute("clazz", expect.stringContaining("bar"))`,
+    `expect(el).toHaveProperty("class", "foo")`,
+    `expect(el).toHaveProperty("clazz", "foo")`,
+    `expect(el).not.toHaveProperty("clazz", "foo")`,
+    `expect(el).toHaveProperty("clazz", expect.stringContaining("bar"))`,
+    `expect(el).not.toHaveProperty("clazz", expect.stringContaining("bar"))`,
+    `expect(closeButton).toHaveAttribute("class", expect.stringMatching("bar"));`,
+  ],
+  invalid: [
+    {
+      code: `expect(screen.getByRole("button").className).toBe("foo")`,
+      errors,
+      output: `expect(screen.getByRole("button")).toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(screen.getByRole("button").className).not.toBe("foo")`,
+      errors,
+      output: `expect(screen.getByRole("button")).not.toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el).toHaveProperty("className", "foo")`,
+      errors,
+      output: `expect(el).toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el).toHaveAttribute("class", "foo")`,
+      errors,
+      output: `expect(el).toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el).toHaveAttribute(\`class\`, "foo")`,
+      errors,
+      output: `expect(el).toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el).toHaveAttribute("class", expect.stringContaining("bar"))`,
+      errors,
+      output: `expect(el).toHaveClass("bar")`,
+    },
+    {
+      code: `expect(el).toHaveAttribute(\`class\`, expect.stringContaining("bar"))`,
+      errors,
+      output: `expect(el).toHaveClass("bar")`,
+    },
+    {
+      code: `expect(el).not.toHaveProperty("className", "foo")`,
+      errors,
+      output: `expect(el).not.toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el).not.toHaveAttribute("class", "foo")`,
+      errors,
+      output: `expect(el).not.toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el.className).toContain("foo")`,
+      errors,
+      output: `expect(el).toHaveClass("foo")`,
+    },
+    {
+      code: `expect(el.className).not.toContain("foo")`,
+      errors,
+      output: `expect(el).not.toHaveClass("foo")`,
+    },
+    {
+      code: `expect(el.className).toBe("foo")`,
+      errors,
+      output: `expect(el).toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el.className).toEqual("foo")`,
+      errors,
+      output: `expect(el).toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el.className).toStrictEqual("foo")`,
+      errors,
+      output: `expect(el).toHaveClass("foo", { exact: true })`,
+    },
+    {
+      code: `expect(el.className).toEqual(expect.stringContaining("foo"))`,
+      errors,
+      output: `expect(el).toHaveClass("foo")`,
+    },
+    {
+      code: `expect(el.className).toEqual(expect.stringContaining(\`foo\`))`,
+      errors,
+      output: `expect(el).toHaveClass(\`foo\`)`,
+    },
+    {
+      code: `expect(el.className).toStrictEqual(expect.stringContaining("foo"))`,
+      errors,
+      output: `expect(el).toHaveClass("foo")`,
+    },
+    {
+      code: `expect(el.className).toEqual(expect.stringContaining("bar"))`,
+      errors,
+      output: `expect(el).toHaveClass("bar")`,
+    },
+    {
+      code: `expect(el.classList).toContain("bar")`,
+      errors,
+      output: `expect(el).toHaveClass("bar")`,
+    },
+    {
+      code: `expect(el.classList).toBe("bar")`,
+      errors,
+    },
+    {
+      code: `expect(el.classList[0]).toBe("bar")`,
+      errors,
+      output: `expect(el).toHaveClass("bar")`,
+    },
+    {
+      code: `expect(el.classList[0]).not.toBe("bar")`,
+      errors,
+    },
+    {
+      code: `expect(el.classList[0]).toContain(("fo"))`,
+      errors,
+    },
+  ],
+});