FP no-duplicate-string: ignore JS directives (#141)

Author: yassin-kammoun-sonarsource

docs/rules/no-duplicate-string.md

@@ -3,7 +3,7 @@ Duplicated string literals make the process of refactoring error-prone, since yo
 On the other hand, constants can be referenced from many places, but only need to be updated in a single place.
 
 ## Exceptions
-To prevent generating some false-positives, literals having less than 10 characters are excluded as well as literals matching /^\w*$/. String literals inside import/export statements are also ignored.
+To prevent generating some false-positives, literals having less than 10 characters are excluded as well as literals matching /^\w*$/. String literals inside import/export statements are also ignored. The same goes for statement-like string literals, e.g. `'use strict';`
 
 ## Configuration
 
@@ -14,4 +14,4 @@ Number of times a literal must be duplicated to trigger an issue. Default is 3.
   "no-duplicate-string": "error",
   "no-duplicate-string": ["error", 5]
 }
-```
+```

ruling/snapshots/no-duplicate-string

@@ -167,7 +167,7 @@ src/jest/packages/jest-util/src/fake_timers.js: 176
 src/jquery/external/npo/npo.js: 5
 src/jquery/external/qunit/qunit.js: 986,1939,2533,2535,2581,2756,2856,3014,3100
 src/jquery/external/requirejs/require.js: 358,359
-src/jquery/external/sinon/sinon.js: 37,538,1355,2394,3129,3146,4665
+src/jquery/external/sinon/sinon.js: 538,1355,2394,3129,3146,4665
 src/jquery/src/deferred.js: 59
 src/react-native/IntegrationTests/ImageCachePolicyTest.js: 32,32,66
 src/react-native/Libraries/Components/Keyboard/Keyboard.js: 111
@@ -181,7 +181,6 @@ src/react-native/Libraries/StyleSheet/TransformPropTypes.js: 86
 src/react-native/Libraries/Utilities/BackAndroid.js: 25
 src/react-native/Libraries/Utilities/PerformanceLogger.js: 74
 src/react-native/Libraries/polyfills/Object.es6.js: 24
-src/react-native/Libraries/polyfills/String.prototype.es6.js: 20
 src/react-native/Libraries/vendor/core/toIterator.js: 27
 src/react-native/RNTester/js/AlertExample.js: 37,49
 src/react-native/RNTester/js/AlertIOSExample.js: 68,113

src/rules/no-duplicate-string.ts

@@ -42,7 +42,8 @@ const rule: Rule.RuleModule = {
     return {
       Literal: (node: Node) => {
         const literal = node as SimpleLiteral;
-        if (typeof literal.value === "string") {
+        const parent = getParent(context);
+        if (typeof literal.value === "string" && (parent && parent.type !== "ExpressionStatement")) {
           const stringContent = literal.value.trim();
 
           if (

tests/rules/no-duplicate-string.test.ts

@@ -133,6 +133,13 @@ ruleTester.run("no-duplicate-string", rule, {
       "some property": 1
     };`,
     },
+    {
+      code: `
+      'use strict';
+      'use strict';
+      'use strict';
+      `,
+    },
   ],
   invalid: [
     {