Add newline-after-import rule

README.md

@@ -54,6 +54,7 @@ This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, a
 * Report namespace imports ([`no-namespace`])
 * Ensure consistent use of file extension within the import path ([`extensions`])
 * Enforce a convention in module import order ([`order`])
+* Enforce a newline after import statements ([`newline-after-import`])
 
 [`imports-first`]: ./docs/rules/imports-first.md
 [`no-duplicates`]: ./docs/rules/no-duplicates.md

docs/rules/newline-after-import.md

@@ -0,0 +1,40 @@
+# newline-after-import
+
+Reports if there's no new line after last import/require in group.
+
+## Rule Details
+
+**NOTE**: In each of those examples you can replace `import` call with `require`.
+
+Valid:
+
+```js
+import defaultExport from './foo'
+
+const FOO = 'BAR'
+```
+
+```js
+import defaultExport from './foo'
+import { bar }  from 'bar-lib'
+
+const FOO = 'BAR'
+```
+
+...whereas here imports will be reported:
+
+```js
+import * as foo from 'foo'
+const FOO = 'BAR'
+```
+
+```js
+import * as foo from 'foo'
+const FOO = 'BAR'
+
+import { bar }  from 'bar-lib'
+```
+
+## When Not To Use It
+
+If you like to visually group module imports with its usage, you don't want to use this rule.

src/index.js

@@ -17,6 +17,7 @@ export const rules = {
   'no-extraneous-dependencies': require('./rules/no-extraneous-dependencies'),
   'no-nodejs-modules': require('./rules/no-nodejs-modules'),
   'order': require('./rules/order'),
+  'newline-after-import': require('./rules/newline-after-import'),
 
   // metadata-based
   'no-deprecated': require('./rules/no-deprecated'),

src/rules/newline-after-import.js

@@ -0,0 +1,50 @@
+/**
+ * @fileoverview Rule to enforce new line after import not followed by another import.
+ * @author Radek Benkel
+ */
+
+import isStaticRequire from '../core/staticRequire'
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+function getLineDifference(node, nextToken) {
+  return nextToken.loc.start.line - node.loc.start.line
+}
+
+function ensureNoForbiddenKeyword(context, node, tokenToInspect, tokenValue) {
+  if (!tokenToInspect) {
+    return
+  }
+
+  if (getLineDifference(node, tokenToInspect) === 1
+    && tokenToInspect.type === 'Keyword' && tokenToInspect.value !== tokenValue)
+  {
+    context.report({
+      loc: tokenToInspect.loc.start,
+      message: 'Expected empty line after ' + tokenValue +
+        ' statement not followed by another ' + tokenValue + '.',
+    })
+  }
+}
+
+module.exports = function (context) {
+  return {
+    ImportDeclaration: function (node) {
+      const nextToken = context.getSourceCode(node).getTokenAfter(node)
+
+      ensureNoForbiddenKeyword(context, node, nextToken, 'import')
+    },
+    CallExpression: function(node) {
+      if (isStaticRequire(node)) {
+        const nextTokens = context.getSourceCode(node).getTokensAfter(node, 2)
+        const tokenToInspect = nextTokens.length > 1 && nextTokens[0].type === 'Punctuator'
+          ? nextTokens[1]
+          : nextTokens[0]
+
+        ensureNoForbiddenKeyword(context, node, tokenToInspect, 'require')
+      }
+    },
+  }
+}

tests/src/rules/newline-after-import.js

@@ -0,0 +1,101 @@
+import { RuleTester } from 'eslint'
+
+const IMPORT_ERROR_MESSAGE = 'Expected empty line after import statement not followed by another import.';
+const REQUIRE_ERROR_MESSAGE = 'Expected empty line after require statement not followed by another require.';
+
+const ruleTester = new RuleTester()
+
+ruleTester.run('newline-after-import', require('rules/newline-after-import'), {
+  valid: [
+    {
+      code: "import foo from 'foo';\n\nvar foo = 'bar';",
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "var foo = require('foo-module');\n\nvar foo = 'bar';",
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "require('foo-module');\n\nvar foo = 'bar';",
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "import foo from 'foo';\nimport { bar } from './bar-lib';",
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "import foo from 'foo';\n\nvar a = 123;\n\nimport { bar } from './bar-lib';",
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "var foo = require('foo-module');\n\nvar a = 123;\n\nvar bar = require('bar-lib');",
+      parserOptions: { sourceType: 'module' }
+    }
+  ],
+
+  invalid: [
+    {
+      code: "import foo from 'foo';\nexport default function() {};",
+      errors: [ {
+        line: 2,
+        column: 1,
+        message: IMPORT_ERROR_MESSAGE
+      } ],
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "var foo = require('foo-module');\nvar something = 123;",
+      errors: [ {
+        line: 2,
+        column: 1,
+        message: REQUIRE_ERROR_MESSAGE
+      } ],
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "import foo from 'foo';\nvar a = 123;\n\nimport { bar } from './bar-lib';\nvar b=456;",
+      errors: [
+      {
+        line: 2,
+        column: 1,
+        message: IMPORT_ERROR_MESSAGE
+      },
+      {
+        line: 5,
+        column: 1,
+        message: IMPORT_ERROR_MESSAGE
+      }],
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "var foo = require('foo-module');\nvar a = 123;\n\nvar bar = require('bar-lib');\nvar b=456;",
+      errors: [
+        {
+          line: 2,
+          column: 1,
+          message: REQUIRE_ERROR_MESSAGE
+        },
+        {
+          line: 5,
+          column: 1,
+          message: REQUIRE_ERROR_MESSAGE
+        }],
+      parserOptions: { sourceType: 'module' }
+    },
+    {
+      code: "var foo = require('foo-module');\nvar a = 123;\n\nrequire('bar-lib');\nvar b=456;",
+      errors: [
+        {
+          line: 2,
+          column: 1,
+          message: REQUIRE_ERROR_MESSAGE
+        },
+        {
+          line: 5,
+          column: 1,
+          message: REQUIRE_ERROR_MESSAGE
+        }],
+      parserOptions: { sourceType: 'module' }
+    },
+  ]
+});