Fix "should_instrument" decision when given negative testMatch pattern

CHANGELOG.md

@@ -39,6 +39,7 @@
 - `[jest-config]` Moved dynamically assigned `cwd` from `jest-cli` to default configuration in `jest-config` ([#7146](https://github.com/facebook/jest/pull/7146))
 - `[jest-config]` Fix `getMaxWorkers` on termux ([#7154](https://github.com/facebook/jest/pull/7154))
 - `[jest-runtime]` Throw an explicit error if `js` is missing from `moduleFileExtensions` ([#7160](https://github.com/facebook/jest/pull/7160))
+- `[jest-runtime]` Fix missing coverage when using negative glob pattern in `testMatch` ([#7170](https://github.com/facebook/jest/pull/7170))
 
 ### Chore & Maintenance
 

packages/jest-runtime/src/__tests__/should_instrument.test.js

@@ -35,14 +35,13 @@ describe('should_instrument', () => {
 
     it('when testMatch is provided and file is not a test file', () => {
       testShouldInstrument('source_file.js', defaultOptions, {
-        testMatch: ['**/?(*.)(test).js'],
+        testMatch: ['**/?(*.)(test).js', '!**/dont/**/*.js'],
       });
     });
 
     it('should return true when file is in collectCoverageOnlyFrom when provided', () => {
       testShouldInstrument(
         'collect/only/from/here.js',
-
         {
           collectCoverage: true,
           collectCoverageOnlyFrom: {'collect/only/from/here.js': true},

packages/jest-runtime/src/should_instrument.js

@@ -42,7 +42,7 @@ export default function shouldInstrument(
   if (
     config.testMatch &&
     config.testMatch.length &&
-    micromatch.any(filename, config.testMatch)
+    micromatch([filename], config.testMatch).length
   ) {
     return false;
   }