⭐️New: Add rule no-boolean-default (#612)

* no-boolean-default

* Rule files

* PR changes

* Added docs

* Added more tests

* Update implementation

* Update config and docs

docs/rules/README.md

@@ -149,6 +149,7 @@ For example:
 | [vue/eqeqeq](./eqeqeq.md) | require the use of `===` and `!==` | :wrench: |
 | [vue/key-spacing](./key-spacing.md) | enforce consistent spacing between keys and values in object literal properties | :wrench: |
 | [vue/match-component-file-name](./match-component-file-name.md) | require component name property to match its file name |  |
+| [vue/no-boolean-default](./no-boolean-default.md) | disallow boolean defaults | :wrench: |
 | [vue/no-restricted-syntax](./no-restricted-syntax.md) | disallow specified syntax |  |
 | [vue/object-curly-spacing](./object-curly-spacing.md) | enforce consistent spacing inside braces | :wrench: |
 | [vue/require-direct-export](./require-direct-export.md) | require the component to be directly exported |  |

docs/rules/no-boolean-default.md

@@ -0,0 +1,49 @@
+---
+pageClass: rule-details
+sidebarDepth: 0
+title: vue/no-boolean-default
+description: disallow boolean defaults
+---
+# vue/no-boolean-default
+> disallow boolean defaults
+
+- :wrench: The `--fix` option on the [command line](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems) can automatically fix some of the problems reported by this rule.
+
+The rule prevents Boolean props from having a default value.
+
+
+## :book: Rule Details
+The rule is to enforce the HTML standard of always defaulting boolean attributes to false.
+
+<eslint-code-block fix :rules="{'vue/no-boolean-default': ['error']}">
+
+```vue
+<script>
+export default {
+  props: {
+    foo: {
+      type: Boolean,
+      default: true
+    },
+    bar: {
+      type: Boolean
+    }
+  }
+}
+</script>
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+- `'no-default'` (default) allows a prop definition object, but enforces that the `default` property not be defined.
+- `'default-false'` enforces that the default can be set but must be set to `false`.
+
+```json
+  "vue/no-boolean-default": ["error", "no-default|default-false"]
+```
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/vuejs/eslint-plugin-vue/blob/master/lib/rules/no-boolean-default.js)
+- [Test source](https://github.com/vuejs/eslint-plugin-vue/blob/master/tests/lib/rules/no-boolean-default.js)

lib/index.js

@@ -32,6 +32,7 @@ module.exports = {
     'mustache-interpolation-spacing': require('./rules/mustache-interpolation-spacing'),
     'name-property-casing': require('./rules/name-property-casing'),
     'no-async-in-computed-properties': require('./rules/no-async-in-computed-properties'),
+    'no-boolean-default': require('./rules/no-boolean-default'),
     'no-confusing-v-for-v-if': require('./rules/no-confusing-v-for-v-if'),
     'no-dupe-keys': require('./rules/no-dupe-keys'),
     'no-duplicate-attributes': require('./rules/no-duplicate-attributes'),

lib/rules/no-boolean-default.js

@@ -0,0 +1,92 @@
+/**
+ * @fileoverview Prevents boolean defaults from being set
+ * @author Hiroki Osame
+ */
+'use strict'
+
+const utils = require('../utils')
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+function isBooleanProp (prop) {
+  return (
+    prop.type === 'Property' &&
+    prop.key.type === 'Identifier' &&
+    prop.key.name === 'type' &&
+    prop.value.type === 'Identifier' &&
+    prop.value.name === 'Boolean'
+  )
+}
+
+function getBooleanProps (props) {
+  return props
+    .filter(prop => (
+      prop.value &&
+      prop.value.properties &&
+      prop.value.properties.find(isBooleanProp)
+    ))
+}
+
+function getDefaultNode (propDef) {
+  return propDef.value.properties.find(p => {
+    return (
+      p.type === 'Property' &&
+      p.key.type === 'Identifier' &&
+      p.key.name === 'default'
+    )
+  })
+}
+
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'disallow boolean defaults',
+      category: undefined,
+      url: 'https://eslint.vuejs.org/rules/no-boolean-default.html'
+    },
+    fixable: 'code',
+    schema: [
+      {
+        enum: ['default-false', 'no-default']
+      }
+    ]
+  },
+
+  create (context) {
+    return utils.executeOnVueComponent(context, (obj) => {
+      const props = utils.getComponentProps(obj)
+      const booleanProps = getBooleanProps(props)
+
+      if (!booleanProps.length) return
+
+      const booleanType = context.options[0] || 'no-default'
+
+      booleanProps.forEach((propDef) => {
+        const defaultNode = getDefaultNode(propDef)
+
+        switch (booleanType) {
+          case 'no-default':
+            if (defaultNode) {
+              context.report({
+                node: defaultNode,
+                message: 'Boolean prop should not set a default (Vue defaults it to false).'
+              })
+            }
+            break
+
+          case 'default-false':
+            if (defaultNode.value.value !== false) {
+              context.report({
+                node: defaultNode,
+                message: 'Boolean prop should be defaulted to false.'
+              })
+            }
+            break
+        }
+      })
+    })
+  }
+}

tests/lib/rules/no-boolean-default.js

@@ -0,0 +1,163 @@
+/**
+ * @fileoverview Prevents boolean defaults from being set
+ * @author Hiroki Osame
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+var rule = require('../../../lib/rules/no-boolean-default')
+
+var RuleTester = require('eslint').RuleTester
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+var ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 2018,
+    sourceType: 'module'
+  }
+})
+ruleTester.run('no-boolean-default', rule, {
+
+  valid: [
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            enabled: Boolean
+          }
+        }
+      `
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        const props = {};
+        export default {
+          props: {
+            ...props,
+            enabled: Boolean
+          }
+        }
+      `
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        const data = {};
+        export default {
+          props: {
+            enabled: {
+              type: Boolean,
+              ...data
+            }
+          }
+        }
+      `,
+      options: ['no-default']
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        const data = {};
+        export default {
+          props: {
+            enabled: {
+              type: Boolean,
+              default: false,
+              ...data
+            }
+          }
+        }
+      `,
+      options: ['default-false']
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        const data = {};
+        export default {
+          props: {
+            enabled: data
+          }
+        }
+      `
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        const data = {};
+        export default {
+          props: {
+            enabled: {
+              ...data
+            }
+          }
+        }
+      `
+    }
+  ],
+
+  invalid: [
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            enabled: {
+              type: Boolean,
+              default: true,
+            }
+          }
+        }
+      `,
+      options: ['default-false'],
+      errors: [{
+        message: 'Boolean prop should be defaulted to false.',
+        line: 6
+      }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            enabled: {
+              type: Boolean,
+              default: null,
+            }
+          }
+        }
+      `,
+      options: ['default-false'],
+      errors: [{
+        message: 'Boolean prop should be defaulted to false.',
+        line: 6
+      }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            enabled: {
+              type: Boolean,
+              default: false,
+            }
+          }
+        }
+      `,
+      options: ['no-default'],
+      errors: [{
+        message: 'Boolean prop should not set a default (Vue defaults it to false).',
+        line: 6
+      }]
+    }
+  ]
+})