feat(mutators) Avoid creating some unnecessary mutators for (a && b) …

e2e/test/babel-transpiling/verify/verify.ts

@@ -3,10 +3,10 @@ import { expectMetricsJson } from '../../../helpers';
 describe('Verify stryker has ran correctly', () => {
   it('should report expected score', async () => {
     // File       | % score | # killed | # timeout | # survived | # no cov | # error |
-    // All files  |   57.45 |       27 |         0 |         20 |        0 |       1 |
+    // All files  |   55.56 |       25 |         0 |         20 |        0 |       1 |
     await expectMetricsJson({
-      killed: 27,
-      mutationScore: 57.45,
+      killed: 25,
+      mutationScore: 55.56,
       runtimeErrors: 1,
       survived: 20,
       noCoverage: 0,

e2e/test/cucumber-ts/verify/verify.ts

@@ -5,17 +5,17 @@ describe('After running stryker on a cucumber-ts project', () => {
     await expectMetricsJson({
       killed: 64,
       ignored: 0,
-      survived: 48,
+      survived: 40,
       timeout: 1,
       noCoverage: 39,
       runtimeErrors: 16,
-      mutationScore: 42.76,
+      mutationScore: 45.14,
     });
     /*
     -----------|---------|----------|-----------|------------|----------|---------|
     File       | % score | # killed | # timeout | # survived | # no cov | # error |
     -----------|---------|----------|-----------|------------|----------|---------|
-    All files  |   42.76 |       64 |         1 |         48 |       39 |      16 |
+    All files  |   45.14 |       64 |         1 |         40 |       39 |      16 |
     -----------|---------|----------|-----------|------------|----------|---------|*/
   });
 });

e2e/test/ignore-project/verify/verify.ts

@@ -6,17 +6,17 @@ describe('After running stryker on jest-react project', () => {
   it('should report expected scores', async () => {
     await expectMetricsJson({
       killed: 8,
-      ignored: 29,
+      ignored: 28,
       mutationScore: 53.33,
     });
   });
-  
+
   /*
   -----------|---------|----------|-----------|------------|----------|---------|
   File       | % score | # killed | # timeout | # survived | # no cov | # error |
   -----------|---------|----------|-----------|------------|----------|---------|
   All files  |   53.33 |        8 |         0 |          0 |        7 |       0 |*/
-    
+
 
   it('should report mutants that are disabled by a comment with correct ignore reason', async () => {
     const actualMetricsResult = await readMutationTestingJsonResult();
@@ -33,7 +33,7 @@ describe('After running stryker on jest-react project', () => {
       expect(conditionalMutant.status).eq(MutantStatus.Ignored);
       expect(conditionalMutant.statusReason).eq('Ignore boolean and conditions');
     });
-    
+
     equalityOperatorMutants.forEach((equalityMutant) => {
       expect(equalityMutant.status).eq(MutantStatus.NoCoverage);
     });

e2e/test/jest-react-ts/verify/verify.ts

@@ -3,9 +3,9 @@ import { expectMetricsJson } from '../../../helpers';
 describe('After running stryker on jest-react-ts project', () => {
   it('should report expected scores', async () => {
     await expectMetricsJson({
-      killed: 63,
-      noCoverage: 19,
-      survived: 25,
+      killed: 61,
+      noCoverage: 18,
+      survived: 24,
       timeout: 5,
     });
   });

e2e/test/jest-with-ts/verify/verify.ts

@@ -4,8 +4,8 @@ describe('Verify stryker has ran correctly', () => {
   it('should report correct score', async () => {
     await expectMetricsJson({
       ignored: 0,
-      killed: 17,
-      mutationScore: 62.96,
+      killed: 14,
+      mutationScore: 58.33,
       noCoverage: 0,
       survived: 10,
       timeout: 0,

e2e/test/karma-webpack-with-ts/verify/verify.ts

@@ -4,10 +4,10 @@ describe('Verify stryker has ran correctly', () => {
 
   it('should report correct score', async () => {
     await expectMetrics({
-      mutationScore: 51.67,
+      mutationScore: 50.85,
       compileErrors: 0,
       ignored: 0,
-      killed: 30,
+      killed: 29,
       noCoverage: 15,
       runtimeErrors: 0,
       timeout: 1,

packages/instrumenter/src/mutators/conditional-expression-mutator.ts

@@ -14,6 +14,22 @@ export const conditionalExpressionMutator: NodeMutator = {
       yield types.booleanLiteral(true);
       yield types.booleanLiteral(false);
     } else if (isBooleanExpression(path)) {
+      if (path.parent?.type === 'LogicalExpression') {
+        // For (x || y), do not generate the (true || y) mutation as it
+        // has the same behavior as the (true) mutator, handled in the
+        // isTestOfCondition branch above
+        if (path.parent.operator === '||') {
+          yield types.booleanLiteral(false);
+          return;
+        }
+        // For (x && y), do not generate the (false && y) mutation as it
+        // has the same behavior as the (false) mutator, handled in the
+        // isTestOfCondition branch above
+        if (path.parent.operator === '&&') {
+          yield types.booleanLiteral(true);
+          return;
+        }
+      }
       yield types.booleanLiteral(true);
       yield types.booleanLiteral(false);
     } else if (path.isForStatement() && !path.node.test) {

packages/instrumenter/test/helpers/expect-mutation.ts

@@ -52,6 +52,10 @@ export function expectJSMutation(sut: NodeMutator, originalCode: string, ...expe
       }
     },
   });
-  expect(mutants).lengthOf(expectedReplacements.length);
-  expectedReplacements.forEach((expected) => expect(mutants, `was: ${mutants.join(',')}`).to.include(expected));
+  /* eslint-disable @typescript-eslint/require-array-sort-compare */
+  /* because we know mutants and expectedReplacements are strings */
+  mutants.sort();
+  expectedReplacements.sort();
+  /* eslint-enable @typescript-eslint/require-array-sort-compare */
+  expect(mutants).to.deep.equal(expectedReplacements);
 }

packages/instrumenter/test/unit/mutators/conditional-expression-mutator.spec.ts

@@ -70,6 +70,50 @@ describe(sut.name, () => {
     );
   });
 
+  it('should not mutate (a || b) condition to (a || true)', () => {
+    expectJSMutation(
+      sut,
+      'if (b === 5 || c === 3) { a++ }',
+      'if (true) { a++ }',
+      'if (false) { a++ }',
+      'if (false || c === 3) { a++ }',
+      'if (b === 5 || false) { a++ }'
+    );
+  });
+
+  it('should not mutate (a && b) condition to (a && false)', () => {
+    expectJSMutation(
+      sut,
+      'if (b === 5 && c === 3) { a++ }',
+      'if (true) { a++ }',
+      'if (false) { a++ }',
+      'if (true && c === 3) { a++ }',
+      'if (b === 5 && true) { a++ }'
+    );
+  });
+
+  it('should mutate ((c1 && c2) || (c3 && c4))', () => {
+    expectJSMutation(
+      sut,
+      'if ((c1 && c2) || (c3 && c4)) { a++ }',
+      'if (true) { a++ }',
+      'if (false) { a++ }',
+      'if ((false) || (c3 && c4)) { a++ }',
+      'if ((c1 && c2) || (false)) { a++ }'
+    );
+  });
+
+  it('should mutate ((c1 || c2) && (c3 || c4))', () => {
+    expectJSMutation(
+      sut,
+      'if ((c1 || c2) && (c3 || c4)) { a++ }',
+      'if (true) { a++ }',
+      'if (false) { a++ }',
+      'if ((true) && (c3 || c4)) { a++ }',
+      'if ((c1 || c2) && (true)) { a++ }'
+    );
+  });
+
   it('should mutate an expression to `true` and `false`', () => {
     expectJSMutation(sut, 'if (something) { a++ }', 'if (true) { a++ }', 'if (false) { a++ }');
   });

packages/instrumenter/testResources/instrumenter/lit-html-sample.ts.out.snap

@@ -186,11 +186,11 @@ export class MutationTestReportTotalsComponent extends LitElement {
                   stryCov_9fa48(\\"17\\");
                   let fullName: string = childResult.name;
 
-                  while (stryMutAct_9fa48(\\"19\\") ? !childResult.file || childResult.childResults.length === 1 : stryMutAct_9fa48(\\"18\\") ? false : (stryCov_9fa48(\\"18\\", \\"19\\"), (stryMutAct_9fa48(\\"20\\") ? childResult.file : (stryCov_9fa48(\\"20\\"), !childResult.file)) && (stryMutAct_9fa48(\\"23\\") ? childResult.childResults.length !== 1 : stryMutAct_9fa48(\\"22\\") ? false : stryMutAct_9fa48(\\"21\\") ? true : (stryCov_9fa48(\\"21\\", \\"22\\", \\"23\\"), childResult.childResults.length === 1)))) {
-                    if (stryMutAct_9fa48(\\"24\\")) {
+                  while (stryMutAct_9fa48(\\"19\\") ? !childResult.file || childResult.childResults.length === 1 : stryMutAct_9fa48(\\"18\\") ? false : (stryCov_9fa48(\\"18\\", \\"19\\"), (stryMutAct_9fa48(\\"20\\") ? childResult.file : (stryCov_9fa48(\\"20\\"), !childResult.file)) && (stryMutAct_9fa48(\\"22\\") ? childResult.childResults.length !== 1 : stryMutAct_9fa48(\\"21\\") ? true : (stryCov_9fa48(\\"21\\", \\"22\\"), childResult.childResults.length === 1)))) {
+                    if (stryMutAct_9fa48(\\"23\\")) {
                       {}
                     } else {
-                      stryCov_9fa48(\\"24\\");
+                      stryCov_9fa48(\\"23\\");
                       childResult = childResult.childResults[0];
                       fullName = pathJoin(fullName, childResult.name);
                     }
@@ -204,7 +204,7 @@ export class MutationTestReportTotalsComponent extends LitElement {
         }
       };
 
-      return stryMutAct_9fa48(\\"25\\") ? html\`\` : (stryCov_9fa48(\\"25\\"), html\`
+      return stryMutAct_9fa48(\\"24\\") ? html\`\` : (stryCov_9fa48(\\"24\\"), html\`
       <tbody>
         \${this.renderRow(model.name, model, undefined)} \${renderChildren()}
       </tbody>
@@ -213,26 +213,26 @@ export class MutationTestReportTotalsComponent extends LitElement {
   }
 
   private renderRow(name: string, row: MetricsResult, path: string | undefined) {
-    if (stryMutAct_9fa48(\\"26\\")) {
+    if (stryMutAct_9fa48(\\"25\\")) {
       {}
     } else {
-      stryCov_9fa48(\\"26\\");
+      stryCov_9fa48(\\"25\\");
       const {
         mutationScore
       } = row.metrics;
-      const scoreIsPresent = stryMutAct_9fa48(\\"27\\") ? isNaN(mutationScore) : (stryCov_9fa48(\\"27\\"), !isNaN(mutationScore));
+      const scoreIsPresent = stryMutAct_9fa48(\\"26\\") ? isNaN(mutationScore) : (stryCov_9fa48(\\"26\\"), !isNaN(mutationScore));
       const coloringClass = this.determineColoringClass(mutationScore);
       const mutationScoreRounded = mutationScore.toFixed(2);
-      const progressBarStyle = stryMutAct_9fa48(\\"28\\") ? \`\` : (stryCov_9fa48(\\"28\\"), \`width: \${mutationScore}%\`);
-      return stryMutAct_9fa48(\\"29\\") ? html\`\` : (stryCov_9fa48(\\"29\\"), html\` <tr title=\\"\${row.name}\\">
+      const progressBarStyle = stryMutAct_9fa48(\\"27\\") ? \`\` : (stryCov_9fa48(\\"27\\"), \`width: \${mutationScore}%\`);
+      return stryMutAct_9fa48(\\"28\\") ? html\`\` : (stryCov_9fa48(\\"28\\"), html\` <tr title=\\"\${row.name}\\">
       <td style=\\"width: 32px;\\" class=\\"icon no-border-right\\"
         >\${row.file ? this.fileIcon : this.directoryIcon}</td
       >
       <td width=\\"\\" class=\\"no-border-left\\"
-        >\${(stryMutAct_9fa48(\\"32\\") ? typeof path !== 'string' : stryMutAct_9fa48(\\"31\\") ? false : stryMutAct_9fa48(\\"30\\") ? true : (stryCov_9fa48(\\"30\\", \\"31\\", \\"32\\"), typeof path === (stryMutAct_9fa48(\\"33\\") ? \\"\\" : (stryCov_9fa48(\\"33\\"), 'string')))) ? stryMutAct_9fa48(\\"34\\") ? html\`\` : (stryCov_9fa48(\\"34\\"), html\`<a href=\\"\${toAbsoluteUrl(path)}\\">\${name}</a>\`) : stryMutAct_9fa48(\\"35\\") ? html\`\` : (stryCov_9fa48(\\"35\\"), html\`<span>\${row.name}</span>\`)}</td
+        >\${(stryMutAct_9fa48(\\"31\\") ? typeof path !== 'string' : stryMutAct_9fa48(\\"30\\") ? false : stryMutAct_9fa48(\\"29\\") ? true : (stryCov_9fa48(\\"29\\", \\"30\\", \\"31\\"), typeof path === (stryMutAct_9fa48(\\"32\\") ? \\"\\" : (stryCov_9fa48(\\"32\\"), 'string')))) ? stryMutAct_9fa48(\\"33\\") ? html\`\` : (stryCov_9fa48(\\"33\\"), html\`<a href=\\"\${toAbsoluteUrl(path)}\\">\${name}</a>\`) : stryMutAct_9fa48(\\"34\\") ? html\`\` : (stryCov_9fa48(\\"34\\"), html\`<span>\${row.name}</span>\`)}</td
       >
       <td class=\\"no-border-right vertical-middle\\">
-        \${scoreIsPresent ? stryMutAct_9fa48(\\"36\\") ? html\`\` : (stryCov_9fa48(\\"36\\"), html\` <div class=\\"progress\\">
+        \${scoreIsPresent ? stryMutAct_9fa48(\\"35\\") ? html\`\` : (stryCov_9fa48(\\"35\\"), html\` <div class=\\"progress\\">
               <div
                 class=\\"progress-bar bg-\${coloringClass}\\"
                 role=\\"progressbar\\"
@@ -243,7 +243,7 @@ export class MutationTestReportTotalsComponent extends LitElement {
               >
                 \${mutationScoreRounded}%
               </div>
-            </div>\`) : stryMutAct_9fa48(\\"37\\") ? html\`\` : (stryCov_9fa48(\\"37\\"), html\` <span class=\\"font-weight-bold text-muted\\">N/A</span> \`)}
+            </div>\`) : stryMutAct_9fa48(\\"36\\") ? html\`\` : (stryCov_9fa48(\\"36\\"), html\` <span class=\\"font-weight-bold text-muted\\">N/A</span> \`)}
       </td>
       <td style=\\"width: 50px;\\" class=\\"no-border-left font-weight-bold text-center text-\${coloringClass}\\">
         \${scoreIsPresent ? mutationScoreRounded : undefined}
@@ -263,46 +263,46 @@ export class MutationTestReportTotalsComponent extends LitElement {
   }
 
   private determineColoringClass(mutationScore: number) {
-    if (stryMutAct_9fa48(\\"38\\")) {
+    if (stryMutAct_9fa48(\\"37\\")) {
       {}
     } else {
-      stryCov_9fa48(\\"38\\");
+      stryCov_9fa48(\\"37\\");
 
-      if (stryMutAct_9fa48(\\"41\\") ? !isNaN(mutationScore) || this.thresholds : stryMutAct_9fa48(\\"40\\") ? false : stryMutAct_9fa48(\\"39\\") ? true : (stryCov_9fa48(\\"39\\", \\"40\\", \\"41\\"), (stryMutAct_9fa48(\\"42\\") ? isNaN(mutationScore) : (stryCov_9fa48(\\"42\\"), !isNaN(mutationScore))) && this.thresholds)) {
-        if (stryMutAct_9fa48(\\"43\\")) {
+      if (stryMutAct_9fa48(\\"40\\") ? !isNaN(mutationScore) || this.thresholds : stryMutAct_9fa48(\\"39\\") ? false : stryMutAct_9fa48(\\"38\\") ? true : (stryCov_9fa48(\\"38\\", \\"39\\", \\"40\\"), (stryMutAct_9fa48(\\"41\\") ? isNaN(mutationScore) : (stryCov_9fa48(\\"41\\"), !isNaN(mutationScore))) && this.thresholds)) {
+        if (stryMutAct_9fa48(\\"42\\")) {
           {}
         } else {
-          stryCov_9fa48(\\"43\\");
+          stryCov_9fa48(\\"42\\");
 
-          if (stryMutAct_9fa48(\\"47\\") ? mutationScore >= this.thresholds.low : stryMutAct_9fa48(\\"46\\") ? mutationScore <= this.thresholds.low : stryMutAct_9fa48(\\"45\\") ? false : stryMutAct_9fa48(\\"44\\") ? true : (stryCov_9fa48(\\"44\\", \\"45\\", \\"46\\", \\"47\\"), mutationScore < this.thresholds.low)) {
-            if (stryMutAct_9fa48(\\"48\\")) {
+          if (stryMutAct_9fa48(\\"46\\") ? mutationScore >= this.thresholds.low : stryMutAct_9fa48(\\"45\\") ? mutationScore <= this.thresholds.low : stryMutAct_9fa48(\\"44\\") ? false : stryMutAct_9fa48(\\"43\\") ? true : (stryCov_9fa48(\\"43\\", \\"44\\", \\"45\\", \\"46\\"), mutationScore < this.thresholds.low)) {
+            if (stryMutAct_9fa48(\\"47\\")) {
               {}
             } else {
-              stryCov_9fa48(\\"48\\");
-              return stryMutAct_9fa48(\\"49\\") ? \\"\\" : (stryCov_9fa48(\\"49\\"), 'danger');
+              stryCov_9fa48(\\"47\\");
+              return stryMutAct_9fa48(\\"48\\") ? \\"\\" : (stryCov_9fa48(\\"48\\"), 'danger');
             }
-          } else if (stryMutAct_9fa48(\\"53\\") ? mutationScore >= this.thresholds.high : stryMutAct_9fa48(\\"52\\") ? mutationScore <= this.thresholds.high : stryMutAct_9fa48(\\"51\\") ? false : stryMutAct_9fa48(\\"50\\") ? true : (stryCov_9fa48(\\"50\\", \\"51\\", \\"52\\", \\"53\\"), mutationScore < this.thresholds.high)) {
-            if (stryMutAct_9fa48(\\"54\\")) {
+          } else if (stryMutAct_9fa48(\\"52\\") ? mutationScore >= this.thresholds.high : stryMutAct_9fa48(\\"51\\") ? mutationScore <= this.thresholds.high : stryMutAct_9fa48(\\"50\\") ? false : stryMutAct_9fa48(\\"49\\") ? true : (stryCov_9fa48(\\"49\\", \\"50\\", \\"51\\", \\"52\\"), mutationScore < this.thresholds.high)) {
+            if (stryMutAct_9fa48(\\"53\\")) {
               {}
             } else {
-              stryCov_9fa48(\\"54\\");
-              return stryMutAct_9fa48(\\"55\\") ? \\"\\" : (stryCov_9fa48(\\"55\\"), 'warning');
+              stryCov_9fa48(\\"53\\");
+              return stryMutAct_9fa48(\\"54\\") ? \\"\\" : (stryCov_9fa48(\\"54\\"), 'warning');
             }
           } else {
-            if (stryMutAct_9fa48(\\"56\\")) {
+            if (stryMutAct_9fa48(\\"55\\")) {
               {}
             } else {
-              stryCov_9fa48(\\"56\\");
-              return stryMutAct_9fa48(\\"57\\") ? \\"\\" : (stryCov_9fa48(\\"57\\"), 'success');
+              stryCov_9fa48(\\"55\\");
+              return stryMutAct_9fa48(\\"56\\") ? \\"\\" : (stryCov_9fa48(\\"56\\"), 'success');
             }
           }
         }
       } else {
-        if (stryMutAct_9fa48(\\"58\\")) {
+        if (stryMutAct_9fa48(\\"57\\")) {
           {}
         } else {
-          stryCov_9fa48(\\"58\\");
-          return stryMutAct_9fa48(\\"59\\") ? \\"\\" : (stryCov_9fa48(\\"59\\"), 'default');
+          stryCov_9fa48(\\"57\\");
+          return stryMutAct_9fa48(\\"58\\") ? \\"\\" : (stryCov_9fa48(\\"58\\"), 'default');
         }
       }
     }

packages/instrumenter/testResources/instrumenter/specific-mutants.ts.out.snap

@@ -66,11 +66,11 @@ function stryMutAct_9fa48(id) {
 const a = stryMutAct_9fa48(\\"0\\") ? 1 - 1 : (stryCov_9fa48(\\"0\\"), 1 + 1);
 const b = 1 - 1;
 
-if ((stryMutAct_9fa48(\\"3\\") ? a !== 2 : stryMutAct_9fa48(\\"2\\") ? false : stryMutAct_9fa48(\\"1\\") ? true : (stryCov_9fa48(\\"1\\", \\"2\\", \\"3\\"), a === 2)) && b === 0) {
+if ((stryMutAct_9fa48(\\"2\\") ? a !== 2 : stryMutAct_9fa48(\\"1\\") ? true : (stryCov_9fa48(\\"1\\", \\"2\\"), a === 2)) && b === 0) {
   console.log('a');
 }
 
-if (a === 2 && (stryMutAct_9fa48(\\"6\\") ? b !== 0 : stryMutAct_9fa48(\\"5\\") ? false : stryMutAct_9fa48(\\"4\\") ? true : (stryCov_9fa48(\\"4\\", \\"5\\", \\"6\\"), b === 0))) {
+if (a === 2 && (stryMutAct_9fa48(\\"4\\") ? b !== 0 : stryMutAct_9fa48(\\"3\\") ? true : (stryCov_9fa48(\\"3\\", \\"4\\"), b === 0))) {
   console.log('b');
 }
 
@@ -80,5 +80,5 @@ const itemWithLongName = {
   longPropertyName3: 3
 };
 
-const item = () => stryMutAct_9fa48(\\"9\\") ? itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName2 || itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName3 : stryMutAct_9fa48(\\"8\\") ? false : stryMutAct_9fa48(\\"7\\") ? true : (stryCov_9fa48(\\"7\\", \\"8\\", \\"9\\"), (stryMutAct_9fa48(\\"12\\") ? itemWithLongName.longPropertyName1 !== itemWithLongName.longPropertyName2 : stryMutAct_9fa48(\\"11\\") ? false : stryMutAct_9fa48(\\"10\\") ? true : (stryCov_9fa48(\\"10\\", \\"11\\", \\"12\\"), itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName2)) && (stryMutAct_9fa48(\\"15\\") ? itemWithLongName.longPropertyName1 !== itemWithLongName.longPropertyName3 : stryMutAct_9fa48(\\"14\\") ? false : stryMutAct_9fa48(\\"13\\") ? true : (stryCov_9fa48(\\"13\\", \\"14\\", \\"15\\"), itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName3)));"
+const item = () => stryMutAct_9fa48(\\"7\\") ? itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName2 || itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName3 : stryMutAct_9fa48(\\"6\\") ? false : stryMutAct_9fa48(\\"5\\") ? true : (stryCov_9fa48(\\"5\\", \\"6\\", \\"7\\"), (stryMutAct_9fa48(\\"9\\") ? itemWithLongName.longPropertyName1 !== itemWithLongName.longPropertyName2 : stryMutAct_9fa48(\\"8\\") ? true : (stryCov_9fa48(\\"8\\", \\"9\\"), itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName2)) && (stryMutAct_9fa48(\\"11\\") ? itemWithLongName.longPropertyName1 !== itemWithLongName.longPropertyName3 : stryMutAct_9fa48(\\"10\\") ? true : (stryCov_9fa48(\\"10\\", \\"11\\"), itemWithLongName.longPropertyName1 === itemWithLongName.longPropertyName3)));"
 `;