Add support for class properties in no-dupe-class-members

Fixes: eslint/eslint#7534 Stage 3 Proposal: https://github.com/tc39/proposal-class-fields Babel plugin: https://babeljs.io/docs/en/babel-plugin-proposal-class-properties This does not yet support private class properties yet as that would require upgrading to babel-eslint@^11 which would require a bunch of other changes. See: babel/babel-eslint#523
Graham42 · Jan 29, 2019 · 5462cfc · 5462cfc
1 parent 37e8ea7
commit 5462cfc
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diff --git a/rules/no-dupe-class-members.js b/rules/no-dupe-class-members.js
@@ -77,6 +77,36 @@ module.exports = {
       }
     }
 
+    /**
+     * Reports the node if its name has been declared already.
+     *
+     * @param {ASTNode} node - A node to get the name.
+     */
+    function checkIfDuplicate(node) {
+      if (node.computed) {
+        return;
+      }
+
+      const name = getName(node.key);
+      const state = getState(name, node.static);
+      let isDuplicate = false;
+
+      if (node.kind === "get") {
+        isDuplicate = state.init || state.get;
+        state.get = true;
+      } else if (node.kind === "set") {
+        isDuplicate = state.init || state.set;
+        state.set = true;
+      } else {
+        isDuplicate = state.init || state.get || state.set;
+        state.init = true;
+      }
+
+      if (isDuplicate) {
+        context.report({ node, messageId: "unexpected", data: { name } });
+      }
+    }
+
     return {
       // Initializes the stack of state of member declarations.
       Program() {
@@ -93,30 +123,12 @@ module.exports = {
         stack.pop();
       },
 
-      // Reports the node if its name has been declared already.
+      ClassProperty(node) {
+        checkIfDuplicate(node);
+      },
+
       MethodDefinition(node) {
-        if (node.computed) {
-          return;
-        }
-
-        const name = getName(node.key);
-        const state = getState(name, node.static);
-        let isDuplicate = false;
-
-        if (node.kind === "get") {
-          isDuplicate = state.init || state.get;
-          state.get = true;
-        } else if (node.kind === "set") {
-          isDuplicate = state.init || state.set;
-          state.set = true;
-        } else {
-          isDuplicate = state.init || state.get || state.set;
-          state.init = true;
-        }
-
-        if (isDuplicate) {
-          context.report({ node, messageId: "unexpected", data: { name } });
-        }
+        checkIfDuplicate(node);
       }
     };
   }

diff --git a/tests/rules/no-dupe-class-members.js b/tests/rules/no-dupe-class-members.js
@@ -21,7 +21,7 @@ const RuleTester = require("../RuleTester");
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester();
 
 ruleTester.run("no-dupe-class-members", rule, {
   valid: [
@@ -34,7 +34,13 @@ ruleTester.run("no-dupe-class-members", rule, {
     "class A { 'foo'() {} 'bar'() {} baz() {} }",
     "class A { *'foo'() {} *'bar'() {} *baz() {} }",
     "class A { get 'foo'() {} get 'bar'() {} get baz() {} }",
-    "class A { 1() {} 2() {} }"
+    "class A { 1() {} 2() {} }",
+    "class A { foo = 1; bar = 1; }",
+    "class A { static foo = 1; foo = 1; }",
+    "class A { foo = 1; } class B { foo = 1; }",
+    "class A { [foo] = 1; foo = 1; }",
+    "class A { foo; bar = 1; }",
+    "class A { foo = () => {}; bar = () => {}; }"
   ],
   invalid: [
     {
@@ -139,6 +145,73 @@ ruleTester.run("no-dupe-class-members", rule, {
           data: { name: "foo" }
         }
       ]
+    },
+    {
+      code: "class A { foo = 1; foo = 1; }",
+      errors: [
+        {
+          type: "ClassProperty",
+          line: 1,
+          column: 20,
+          messageId: "unexpected",
+          data: { name: "foo" }
+        }
+      ]
+    },
+    {
+      code: "class A { foo = 1; foo = 1; foo = 1; }",
+      errors: [
+        {
+          type: "ClassProperty",
+          line: 1,
+          column: 20,
+          messageId: "unexpected",
+          data: { name: "foo" }
+        },
+        {
+          type: "ClassProperty",
+          line: 1,
+          column: 29,
+          messageId: "unexpected",
+          data: { name: "foo" }
+        }
+      ]
+    },
+    {
+      code: "class A { static foo = 1; static foo = 1; }",
+      errors: [
+        {
+          type: "ClassProperty",
+          line: 1,
+          column: 27,
+          messageId: "unexpected",
+          data: { name: "foo" }
+        }
+      ]
+    },
+    {
+      code: "class A { 'foo' = 1; 'foo' = 1; }",
+      errors: [
+        {
+          type: "ClassProperty",
+          line: 1,
+          column: 22,
+          messageId: "unexpected",
+          data: { name: "foo" }
+        }
+      ]
+    },
+    {
+      code: "class A { foo = () => {}; foo = () => {}; }",
+      errors: [
+        {
+          type: "ClassProperty",
+          line: 1,
+          column: 27,
+          messageId: "unexpected",
+          data: { name: "foo" }
+        }
+      ]
     }
   ]
 });