Forbid testMatch and testRegex being used together

packages/jest-config/src/__tests__/__snapshots__/normalize-test.js.snap

@@ -44,3 +44,13 @@ exports[`testEnvironment throws on invalid environment names 1`] = `
   https://facebook.github.io/jest/docs/configuration.html
 "
 `;
+
+exports[`testMatch throws if testRegex and testMatch are both specified 1`] = `
+"● Validation Error:
+
+  Configuration options testMatch and testRegex cannot be used together.
+
+  Configuration Documentation:
+  https://facebook.github.io/jest/docs/configuration.html
+"
+`;

packages/jest-config/src/__tests__/normalize-test.js

@@ -589,6 +589,16 @@ describe('testMatch', () => {
 
     expect(config.testRegex).toBe('');
   });
+
+  it('throws if testRegex and testMatch are both specified', () => {
+    expect(() => {
+      normalize({
+        rootDir: '/root',
+        testMatch: ['**/*.js'],
+        testRegex: '.*',
+      });
+    }).toThrowErrorMatchingSnapshot();
+  });
 });
 
 describe('preset', () => {

packages/jest-config/src/normalize.js

@@ -372,6 +372,13 @@ function normalize(config: InitialConfig, argv: Object = {}) {
     }
   }
 
+  if (config.testRegex && config.testMatch) {
+    throw createConfigError(
+      `  Configuration options ${chalk.bold('testMatch')} and` +
+      ` ${chalk.bold('testRegex')} cannot be used together.`
+    );
+  }
+
   if (config.testRegex && (!config.testMatch)) {
     // Prevent the default testMatch conflicting with any explicitly
     // configured `testRegex` value