[New] newline-after-import: new option exactCount and docs update

Fixes #1901. Fixes #514.
import-js · Oct 27, 2020 · bb84371 · bb84371
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -14,6 +14,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 - [`no-unused-modules`]: Support destructuring assignment for `export`. ([#1997], thanks [@s-h-a-d-o-w])
 - [`order`]: support type imports ([#2021], thanks [@grit96])
 - [`order`]: Add `warnOnUnassignedImports` option to enable warnings for out of order unassigned imports ([#1990], thanks [@hayes])
+- [`newline-after-import`]: new option `exactCount` and docs update ([#1933], thanks [@anikethsaha])
 
 ### Fixed
 - [`export`]/TypeScript: properly detect export specifiers as children of a TS module block ([#1889], thanks [@andreubotella])

diff --git a/docs/rules/newline-after-import.md b/docs/rules/newline-after-import.md
@@ -5,72 +5,123 @@ Enforces having one or more empty lines after the last top-level import statemen
 
 ## Rule Details
 
-This rule has one option, `count` which sets the number of newlines that are enforced after the last top-level import statement or require call. This option defaults to `1`.
+This rule accepts two options,
+
+1. `count` which sets the number of newlines that are enforced after the last top-level import statement or require call. The number of newlines should be greater than or equal to `count`. This option defaults to `1`.
+
+2. `exactCount` which enforce the exact numbers of newlines that is mentioned in `count`. This option defaults to `false`.
+
 
 Valid:
 
 ```js
-import defaultExport from './foo'
+import defaultExport from './foo';
 
-const FOO = 'BAR'
+const FOO = 'BAR';
 ```
 
 ```js
-import defaultExport from './foo'
-import { bar }  from 'bar-lib'
+import defaultExport from './foo';
+import { bar }  from 'bar-lib';
 
-const FOO = 'BAR'
+const FOO = 'BAR';
 ```
 
 ```js
-const FOO = require('./foo')
-const BAR = require('./bar')
+const FOO = require('./foo');
+const BAR = require('./bar');
 
-const BAZ = 1
+const BAZ = 1;
 ```
 
 Invalid:
 
 ```js
 import * as foo from 'foo'
-const FOO = 'BAR'
+const FOO = 'BAR';
 ```
 
 ```js
-import * as foo from 'foo'
-const FOO = 'BAR'
+import * as foo from 'foo';
+const FOO = 'BAR';
 
-import { bar }  from 'bar-lib'
+import { bar }  from 'bar-lib';
 ```
 
 ```js
-const FOO = require('./foo')
-const BAZ = 1
-const BAR = require('./bar')
+const FOO = require('./foo');
+const BAZ = 1;
+const BAR = require('./bar');
 ```
 
 With `count` set to `2` this will be considered valid:
 
 ```js
-import defaultExport from './foo'
+import defaultExport from './foo';
+
+
+const FOO = 'BAR';
+```
+
+```js
+import defaultExport from './foo';
 
 
-const FOO = 'BAR'
+
+const FOO = 'BAR';
 ```
 
 With `count` set to `2` these will be considered invalid:
 
 ```js
-import defaultExport from './foo'
-const FOO = 'BAR'
+import defaultExport from './foo';
+const FOO = 'BAR';
+```
+
+```js
+import defaultExport from './foo';
+
+const FOO = 'BAR';
+```
+
+With `count` set to `2` and `exactCount` set to `true` this will be considered valid:
+
+```js
+import defaultExport from './foo';
+
+
+const FOO = 'BAR';
+```
+
+With `count` set to `2` and `exactCount` set to `true` these will be considered invalid:
+
+```js
+import defaultExport from './foo';
+const FOO = 'BAR';
+```
+
+```js
+import defaultExport from './foo';
+
+const FOO = 'BAR';
 ```
 
 ```js
-import defaultExport from './foo'
+import defaultExport from './foo';
+
+
 
-const FOO = 'BAR'
+const FOO = 'BAR';
 ```
 
+```js
+import defaultExport from './foo';
+
+
+
+
+const FOO = 'BAR';
+```
 
 ## Example options usage
 ```json

diff --git a/src/rules/newline-after-import.js b/src/rules/newline-after-import.js
@@ -60,14 +60,18 @@ module.exports = {
     fixable: 'whitespace',
     schema: [
       {
-        'type': 'object',
-        'properties': {
-          'count': {
-            'type': 'integer',
-            'minimum': 1,
+        type: 'object',
+        properties: {
+          count: {
+            type: 'integer',
+            minimum: 1,
+          },
+          exactCount: {
+            type: 'boolean',
+            default: false,
           },
         },
-        'additionalProperties': false,
+        additionalProperties: false,
       },
     ],
   },
@@ -86,11 +90,14 @@ module.exports = {
         nextNode = nextNode.decorators[0];
       }
 
-      const options = context.options[0] || { count: 1 };
+      const options = context.options[0] || { count: 1, exactCount: false };
       const lineDifference = getLineDifference(node, nextNode);
       const EXPECTED_LINE_DIFFERENCE = options.count + 1;
 
-      if (lineDifference < EXPECTED_LINE_DIFFERENCE) {
+      if (
+        lineDifference < EXPECTED_LINE_DIFFERENCE
+        || options.exactCount && lineDifference !== EXPECTED_LINE_DIFFERENCE
+      ) {
         let column = node.loc.start.column;
 
         if (node.loc.start.line !== node.loc.end.line) {
@@ -104,10 +111,15 @@ module.exports = {
           },
           message: `Expected ${options.count} empty line${options.count > 1 ? 's' : ''} \
 after ${type} statement not followed by another ${type}.`,
-          fix: fixer => fixer.insertTextAfter(
-            node,
-            '\n'.repeat(EXPECTED_LINE_DIFFERENCE - lineDifference)
-          ),
+          fix: fixer => {
+            if (options.exactCount && EXPECTED_LINE_DIFFERENCE < lineDifference) {
+              return null;
+            }
+            return fixer.insertTextAfter(
+              node,
+              '\n'.repeat(EXPECTED_LINE_DIFFERENCE - lineDifference)
+            );
+          },
         });
       }
     }
@@ -137,7 +149,7 @@ after ${type} statement not followed by another ${type}.`,
     return {
       ImportDeclaration: checkImport,
       TSImportEqualsDeclaration: checkImport,
-      CallExpression: function(node) {
+      CallExpression: function (node) {
         if (isStaticRequire(node) && level === 0) {
           requireCalls.push(node);
         }
@@ -159,8 +171,10 @@ after ${type} statement not followed by another ${type}.`,
             return;
           }
 
-          if (nextStatement &&
-             (!nextRequireCall || !containsNodeOrEqual(nextStatement, nextRequireCall))) {
+          if (
+            nextStatement
+            && (!nextRequireCall || !containsNodeOrEqual(nextStatement, nextRequireCall))
+          ) {
 
             checkForNewLine(statementWithRequireCall, nextStatement, 'require');
           }

diff --git a/tests/src/rules/newline-after-import.js b/tests/src/rules/newline-after-import.js
@@ -91,6 +91,21 @@ ruleTester.run('newline-after-import', require('rules/newline-after-import'), {
       parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
       options: [{ 'count': 2 }],
     },
+    {
+      code: `import foo from 'foo';\n\n\nvar bar = 'bar';`,
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+      options: [{ 'count': 2, 'exactCount': true }],
+    },
+    {
+      code: `import foo from 'foo';\n\nvar bar = 'bar';`,
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+      options: [{ 'count': 1, 'exactCount': true }],
+    },
+    {
+      code: `import foo from 'foo';\n\n\nvar bar = 'bar';`,
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+      options: [{ 'count': 1 }],
+    },
     {
       code: `import foo from 'foo';\n\n\n\n\nvar bar = 'bar';`,
       parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
@@ -110,6 +125,11 @@ ruleTester.run('newline-after-import', require('rules/newline-after-import'), {
       parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
       options: [{ 'count': 4 }],
     },
+    {
+      code: `var foo = require('foo-module');\n\n\n\n\nvar foo = 'bar';`,
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+      options: [{ 'count': 4, 'exactCount' : true }],
+    },
     {
       code: `require('foo-module');\n\nvar foo = 'bar';`,
       parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
@@ -453,5 +473,60 @@ ruleTester.run('newline-after-import', require('rules/newline-after-import'), {
       parserOptions: { sourceType: 'module' },
       parser: require.resolve('babel-eslint'),
     })) || [],
+    {
+      code: `import foo from 'foo';\n\nexport default function() {};`,
+      output: `import foo from 'foo';\n\n\nexport default function() {};`,
+      options: [{ 'count': 2, exactCount: true }],
+      errors: [ {
+        line: 1,
+        column: 1,
+        message: IMPORT_ERROR_MESSAGE_MULTIPLE(2),
+      } ],
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+    },
+    {
+      code: `import foo from 'foo';\n\n\n\nexport default function() {};`,
+      output: null,
+      options: [{ 'count': 2, exactCount: true }],
+      errors: [ {
+        line: 1,
+        column: 1,
+        message: IMPORT_ERROR_MESSAGE_MULTIPLE(2),
+      } ],
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+    },
+    {
+      code: `import foo from 'foo';\n\n\n\n\nexport default function() {};`,
+      output: null,
+      options: [{ 'count': 2, exactCount: true }],
+      errors: [ {
+        line: 1,
+        column: 1,
+        message: IMPORT_ERROR_MESSAGE_MULTIPLE(2),
+      } ],
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+    },
+    {
+      code: `import foo from 'foo';export default function() {};`,
+      output: `import foo from 'foo';\n\nexport default function() {};`,
+      options: [{ 'count': 1, exactCount: true }],
+      errors: [ {
+        line: 1,
+        column: 1,
+        message: IMPORT_ERROR_MESSAGE,
+      } ],
+      parserOptions: { ecmaVersion: 2015, sourceType: 'module' },
+    },
+    {
+      code: `const foo = require('foo');\n\n\n\nconst bar = function() {};`,
+      output: null,
+      options: [{ 'count': 2, exactCount: true }],
+      errors: [ {
+        line: 1,
+        column: 1,
+        message: 'Expected 2 empty lines after require statement not followed by another require.',
+      } ],
+      parserOptions: { ecmaVersion: 2015 },
+    },
   ),
 });