[New] Add prop-name-casing

docs/rules/prop-name-casing.md

@@ -0,0 +1,35 @@
+# enforce specific casing for the Prop name in Vue components(prop-name-casing)
+
+This rule would enforce proper casing of props in vue components(camelCase).
+
+## :book: Rule Details
+
+(https://vuejs.org/v2/style-guide/#Prop-name-casing-strongly-recommended).
+
+:+1: Examples of **correct** code for `camelCase`:
+
+```js
+export default {
+  props: {
+    greetingText: String
+  }
+}
+```
+
+:-1: Examples of **incorrect** code for `camelCase`:
+
+```js
+export default {
+  props: {
+    'greeting-text': String
+  }
+}
+```
+
+## :wrench: Options
+
+Default casing is set to `camelCase`.
+
+```
+"vue/prop-name-casing": ["error", "camelCase|snake_case"]
+```

lib/rules/prop-name-casing.js

@@ -0,0 +1,73 @@
+/**
+ * @fileoverview Requires specific casing for the Prop name in Vue components
+ * @author Yu Kimura
+ */
+'use strict'
+
+const utils = require('../utils')
+const casing = require('../utils/casing')
+const allowedCaseOptions = ['camelCase', 'snake_case']
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+function create (context) {
+  const options = context.options[0]
+  const caseType = allowedCaseOptions.indexOf(options) !== -1 ? options : 'camelCase'
+  const converter = casing.getConverter(caseType)
+
+  // ----------------------------------------------------------------------
+  // Public
+  // ----------------------------------------------------------------------
+
+  return utils.executeOnVue(context, (obj) => {
+    const node = obj.properties.find(p =>
+      p.type === 'Property' &&
+      p.key.type === 'Identifier' &&
+      p.key.name === 'props'
+    )
+    if (!node) return
+
+    const items = node.value.type === 'ObjectExpression' ? node.value.properties : node.value.elements
+    for (const item of items) {
+      if (item.type !== 'Property') {
+        return
+      }
+
+      const propName = item.key.type === 'Literal' ? item.key.value : item.key.name
+      const convertedName = converter(propName)
+      if (convertedName !== propName) {
+        context.report({
+          node: item,
+          message: 'Prop "{{name}}" is not {{caseType}}.',
+          data: {
+            name: propName,
+            caseType: caseType
+          }
+        })
+      }
+    }
+  })
+}
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  meta: {
+    docs: {
+      description: 'enforce specific casing for the Prop name in Vue components',
+      category: 'strongly-recommended'
+    },
+    fixable: null,  // or "code" or "whitespace"
+    schema: [
+      {
+        enum: allowedCaseOptions
+      }
+    ]
+  },
+
+  create
+}

lib/utils/casing.js

@@ -14,6 +14,18 @@ function kebabCase (str) {
     .toLowerCase()
 }
 
+/**
+ * Convert text to snake_case
+ * @param {string} str Text to be converted
+ * @return {string}
+ */
+function snakeCase (str) {
+  return str
+    .replace(/([a-z])([A-Z])/g, match => match[0] + '_' + match[1])
+    .replace(invalidChars, '_')
+    .toLowerCase()
+}
+
 /**
  * Convert text to camelCase
  * @param {string} str Text to be converted
@@ -42,6 +54,7 @@ function pascalCase (str) {
 
 const convertersMap = {
   'kebab-case': kebabCase,
+  'snake_case': snakeCase,
   'camelCase': camelCase,
   'PascalCase': pascalCase
 }

tests/lib/rules/prop-name-casing.js

@@ -0,0 +1,180 @@
+/**
+ * @fileoverview Define a style for the name property casing for consistency purposes
+ * @author Yu Kimura
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const rule = require('../../../lib/rules/prop-name-casing')
+const RuleTester = require('eslint').RuleTester
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const parserOptions = {
+  ecmaVersion: 6,
+  sourceType: 'module',
+  ecmaFeatures: { experimentalObjectRestSpread: true }
+}
+
+const ruleTester = new RuleTester()
+ruleTester.run('prop-name-casing', rule, {
+
+  valid: [
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: ['greetingText']
+        }
+      `,
+      parserOptions
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: ['greetingText']
+        }
+      `,
+      options: ['camelCase'],
+      parserOptions
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: ['greetingText']
+        }
+      `,
+      options: ['snake_case'],
+      parserOptions
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            greetingText: String
+          }
+        }
+      `,
+      parserOptions
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      export default {
+        props: {
+          greetingText: String
+        }
+      }
+      `,
+      options: ['camelCase'],
+      parserOptions
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      export default {
+        props: {
+          greeting_text: String
+        }
+      }
+      `,
+      options: ['snake_case'],
+      parserOptions
+    }
+  ],
+
+  invalid: [
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            greeting_text: String
+          }
+        }
+      `,
+      parserOptions,
+      errors: [{
+        message: 'Prop "greeting_text" is not camelCase.',
+        type: 'Property',
+        line: 4
+      }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            greeting_text: String
+          }
+        }
+      `,
+      options: ['camelCase'],
+      parserOptions,
+      errors: [{
+        message: 'Prop "greeting_text" is not camelCase.',
+        type: 'Property',
+        line: 4
+      }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            greetingText: String
+          }
+        }
+      `,
+      options: ['snake_case'],
+      parserOptions,
+      errors: [{
+        message: 'Prop "greetingText" is not snake_case.',
+        type: 'Property',
+        line: 4
+      }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            'greeting-text': String
+          }
+        }
+      `,
+      options: ['camelCase'],
+      parserOptions,
+      errors: [{
+        message: 'Prop "greeting-text" is not camelCase.',
+        type: 'Property',
+        line: 4
+      }]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+        export default {
+          props: {
+            'greeting-text': String
+          }
+        }
+      `,
+      options: ['snake_case'],
+      parserOptions,
+      errors: [{
+        message: 'Prop "greeting-text" is not snake_case.',
+        type: 'Property',
+        line: 4
+      }]
+    }
+  ]
+})

tests/lib/utils/casing.js

@@ -32,4 +32,13 @@ describe('getConverter()', () => {
     assert.ok(converter('FooBar') === 'foo-bar')
     assert.ok(converter('Foo1Bar') === 'foo1bar')
   })
+
+  it('should conver string to snake_case', () => {
+    const converter = casing.getConverter('snake_case')
+
+    assert.ok(converter('fooBar') === 'foo_bar')
+    assert.ok(converter('foo-bar') === 'foo_bar')
+    assert.ok(converter('FooBar') === 'foo_bar')
+    assert.ok(converter('Foo1Bar') === 'foo1bar')
+  })
 })