Detect: import util from "util"

Refs #33
lebab · Sep 18, 2016 · 52c5bc7 · 52c5bc7
1 parent d38812c
commit 52c5bc7
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diff --git a/src/transform/class/inheritance/ImportUtilDetector.js b/src/transform/class/inheritance/ImportUtilDetector.js
@@ -0,0 +1,50 @@
+import {isAstMatch, extract, matchesLength} from '../../../utils/matchesAst';
+
+/**
+ * Detects variable name imported from: import <name> from "util"
+ */
+export default class ImportUtilDetector {
+  /**
+   * Detects: import <identifier> from "util"
+   *
+   * @param {Object} node
+   * @return {Object} MemberExpression of <identifier>.inherits
+   */
+  detect(node) {
+    const m = this.matchImportUtil(node);
+    if (m) {
+      return {
+        type: 'MemberExpression',
+        computed: false,
+        object: {
+          type: 'Identifier',
+          name: m.name,
+        },
+        property: {
+          type: 'Identifier',
+          name: 'inherits'
+        }
+      };
+    }
+  }
+
+  // Matches: import <name> from "util"
+  matchImportUtil(node) {
+    return isAstMatch(node, {
+      type: 'ImportDeclaration',
+      specifiers: matchesLength([
+        {
+          type: 'ImportDefaultSpecifier',
+          local: {
+            type: 'Identifier',
+            name: extract('name')
+          }
+        }
+      ]),
+      source: {
+        type: 'Literal',
+        value: 'util'
+      }
+    });
+  }
+}
diff --git a/src/transform/class/inheritance/UtilInherits.js b/src/transform/class/inheritance/UtilInherits.js
@@ -1,6 +1,7 @@
 import {isAstMatch, extract} from '../../../utils/matchesAst';
 import RequireUtilDetector from './RequireUtilDetector';
 import RequireUtilInheritsDetector from './RequireUtilInheritsDetector';
+import ImportUtilDetector from './ImportUtilDetector';
 
 /**
  * Processes nodes to detect super classes and return information for later
@@ -18,6 +19,7 @@ export default class UtilInherits {
     this.detectors = [
       new RequireUtilDetector(),
       new RequireUtilInheritsDetector(),
+      new ImportUtilDetector(),
     ];
   }
 

diff --git a/test/transform/classInheritanceTest.js b/test/transform/classInheritanceTest.js
@@ -27,6 +27,36 @@ describe('Class Inheritance', () => {
       );
     });
 
+    it('supports import from "util"', () => {
+      expectTransform(
+        'import util from "util";\n' +
+        'function MyClass() {\n' +
+        '}\n' +
+        'util.inherits(MyClass, ParentClass);'
+      ).toReturn(
+        'import util from "util";\n' +
+        'class MyClass extends ParentClass {}'
+      );
+    });
+
+    it('ignores import of anything else than "util"', () => {
+      expectNoChange(
+        'import util from "./util";\n' +
+        'function MyClass() {\n' +
+        '}\n' +
+        'util.inherits(MyClass, ParentClass);'
+      );
+    });
+
+    it('ignores named imports from "util"', () => {
+      expectNoChange(
+        'import {util} from "util";\n' +
+        'function MyClass() {\n' +
+        '}\n' +
+        'util.inherits(MyClass, ParentClass);'
+      );
+    });
+
     it('preserves inheritance when the inherited class is a member expression', () => {
       expectTransform(
         'var util = require("util");\n' +