diff --git a/src/preset.ts b/src/preset.ts
index 66364f7..2c5f677 100644
--- a/src/preset.ts
+++ b/src/preset.ts
@@ -10,23 +10,12 @@ const moduleExtensionRegexp = `(${moduleExtensions.join('|')})`;
 /**
  * Create a Jest preset configuration for Stencil components.
  */
-export function createJestStencilPreset(
-  options: {
-    rootDir?: string;
-    moduleNameMapper?: Record<string, string>;
-  } = {},
-): Config.InitialOptions {
+export function createJestStencilPreset(options: Config.InitialOptions = {}): Config.InitialOptions {
   const preset: Config.InitialOptions = {
     testEnvironment: 'node',
     moduleFileExtensions: [...moduleExtensions, 'json', 'd.ts'],
-    moduleNameMapper: {
-      '^@stencil/core/testing$': 'jest-stencil-runner',
-      '^@stencil/core$': '@stencil/core',
-      ...options.moduleNameMapper,
-    },
     setupFilesAfterEnv: ['jest-stencil-runner/setup'],
     testPathIgnorePatterns: ['/.cache', '/.stencil', '/.vscode', '/dist', '/node_modules', '/www'],
-    testRegex: `${String.raw`(/__tests__/.*|\.?(test|spec))\.` + moduleExtensionRegexp}$`,
     transform: {
       '^.+\\.(ts|tsx|jsx|js|mjs|css)(\\?.*)?$': path.resolve(__dirname, 'preprocessor.js'),
     },
@@ -34,7 +23,17 @@ export function createJestStencilPreset(
     collectCoverageFrom: ['src/**/*.{ts,tsx}', '!src/**/*.d.ts', '!src/**/*.spec.{ts,tsx}', '!src/**/*.e2e.{ts,tsx}'],
     testTimeout: 30000,
     snapshotSerializers: [path.resolve(__dirname, 'snapshot.js')],
+    ...options,
+    moduleNameMapper: {
+      '^@stencil/core/testing$': 'jest-stencil-runner',
+      '^@stencil/core$': '@stencil/core',
+      ...options.moduleNameMapper,
+    },
   };
 
+  if (!options.testMatch && !options.testRegex) {
+    preset.testRegex = `${String.raw`(/__tests__/.*|\.?(test|spec))\.` + moduleExtensionRegexp}$`;
+  }
+
   return preset;
 }