New: rule lines-between-class-methods(fixes eslint#5949).

conf/eslint-recommended.js

@@ -62,6 +62,7 @@ module.exports = {
         "linebreak-style": "off",
         "lines-around-comment": "off",
         "lines-around-directive": "off",
+        "lines-between-class-methods": "off",
         "max-depth": "off",
         "max-len": "off",
         "max-lines": "off",

docs/rules/lines-between-class-methods.md

@@ -0,0 +1,5 @@
+# enforce lines between class methods (lines-between-class-methods)
+
+## Rule Details
+
+## Options

lib/rules/lines-between-class-methods.js

@@ -0,0 +1,106 @@
+/**
+ * @fileoverview Rule to enforce lines between class methods
+ * @author 薛定谔的猫<hh_2013@foxmail.com>
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+// const astUtils = require("../ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "enforce lines between class methods",
+            category: "Stylistic Issues",
+            recommended: false
+        },
+
+        fixable: null,
+
+        schema: [
+            {
+                oneOf: [
+                    {
+                        enum: ["always", "never"]
+                    },
+                    {
+                        type: "object",
+                        properties: {
+                            multiLine: {
+                                enum: ["always", "never"]
+                            },
+                            singleLine: {
+                                enum: ["always", "never"]
+                            }
+                        },
+                        additionalProperties: false,
+                        minProperties: 1
+                    }
+                ]
+            }
+        ]
+    },
+
+    create(context) {
+
+        // const options = {};
+        const config = context.options[0] || "always";
+
+        const ALWAYS_MESSAGE = "Methods must be padded by blank lines.";
+        const NEVER_MESSAGE = "Methods must not be padded by blank lines.";
+
+        const sourceCode = context.getSourceCode();
+
+        /**
+         * Checks if there is padding between two tokens
+         * @param {Token} first The first token
+         * @param {Token} second The second token
+         * @returns {boolean} True if there is at least a line between the tokens
+         */
+        function isPaddingBetweenTokens(first, second) {
+            return second.loc.start.line - first.loc.end.line >= 2;
+        }
+
+        /**
+         * Checks the given BlockStatement node to be padded if the block is not empty.
+         * @param {ASTNode} node The AST node of a BlockStatement.
+         * @returns {void} undefined.
+         */
+        function checkPadding(node) {
+            for (let i = 0; i < node.body.length - 1; i++) {
+                const prev = sourceCode.getLastToken(node.body[i]);
+                const next = sourceCode.getFirstToken(node.body[i + 1]);
+                const padded = isPaddingBetweenTokens(prev, next);
+
+                if (config === "always" && !padded) {
+                    context.report({
+                        node,
+                        message: ALWAYS_MESSAGE
+                    });
+                } else if (config === "never" && padded) {
+                    context.report({
+                        node,
+                        message: NEVER_MESSAGE
+                    });
+                }
+            }
+        }
+
+        return {
+            ClassBody: checkPadding
+        };
+
+    }
+};

tests/lib/rules/lines-between-class-methods.js

@@ -0,0 +1,35 @@
+/**
+ * @fileoverview Tests for lines-between-class-methods rule.
+ * @author 薛定谔的猫<hh_2013@foxmail.com>
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const rule = require("../../../lib/rules/lines-between-class-methods");
+const RuleTester = require("../../../lib/testers/rule-tester");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+const ALWAYS_MESSAGE = "Methods must be padded by blank lines.";
+const NEVER_MESSAGE = "Methods must not be padded by blank lines.";
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+
+ruleTester.run("lines-between-class-methods", rule, {
+    valid: [
+        "class foo{ bar(){}\n\nbaz(){}}"
+    ],
+    invalid: [
+        { code: "class foo{ bar(){}baz(){}}", output: null, errors: [{ message: ALWAYS_MESSAGE }] },
+        { code: "class foo{ bar(){}\n\nbaz(){}}", output: null, options: ["never"], errors: [{ message: NEVER_MESSAGE }] }
+    ]
+});