diff --git a/TestUtils.ts b/TestUtils.ts
index 031f9de0916a..0de81a811a81 100644
--- a/TestUtils.ts
+++ b/TestUtils.ts
@@ -13,38 +13,38 @@ const DEFAULT_GLOBAL_CONFIG: Config.GlobalConfig = {
   changedSince: '',
   collectCoverage: false,
   collectCoverageFrom: [],
-  collectCoverageOnlyFrom: null,
+  collectCoverageOnlyFrom: undefined,
   coverageDirectory: 'coverage',
   coverageProvider: 'babel',
   coverageReporters: [],
   coverageThreshold: {global: {}},
   detectLeaks: false,
   detectOpenHandles: false,
-  enabledTestsMap: null,
+  enabledTestsMap: undefined,
   errorOnDeprecated: false,
   expand: false,
-  filter: null,
+  filter: undefined,
   findRelatedTests: false,
   forceExit: false,
-  globalSetup: null,
-  globalTeardown: null,
+  globalSetup: undefined,
+  globalTeardown: undefined,
   json: false,
   lastCommit: false,
   listTests: false,
   logHeapUsage: false,
   maxConcurrency: 5,
   maxWorkers: 2,
-  noSCM: null,
+  noSCM: undefined,
   noStackTrace: false,
   nonFlagArgs: [],
   notify: false,
   notifyMode: 'failure-change',
   onlyChanged: false,
   onlyFailures: false,
-  outputFile: null,
+  outputFile: undefined,
   passWithNoTests: false,
   projects: [],
-  replname: null,
+  replname: undefined,
   reporters: [],
   rootDir: '/test_root_dir/',
   runTestsByPath: false,
@@ -53,7 +53,7 @@ const DEFAULT_GLOBAL_CONFIG: Config.GlobalConfig = {
   testFailureExitCode: 1,
   testNamePattern: '',
   testPathPattern: '',
-  testResultsProcessor: null,
+  testResultsProcessor: undefined,
   testSequencer: '@jest/test-sequencer',
   testTimeout: 5000,
   updateSnapshot: 'none',
@@ -77,10 +77,10 @@ const DEFAULT_PROJECT_CONFIG: Config.ProjectConfig = {
   displayName: undefined,
   errorOnDeprecated: false,
   extraGlobals: [],
-  filter: null,
+  filter: undefined,
   forceCoverageMatch: [],
-  globalSetup: null,
-  globalTeardown: null,
+  globalSetup: undefined,
+  globalTeardown: undefined,
   globals: {},
   haste: {},
   moduleDirectories: [],
@@ -93,7 +93,7 @@ const DEFAULT_PROJECT_CONFIG: Config.ProjectConfig = {
   prettierPath: 'prettier',
   resetMocks: false,
   resetModules: false,
-  resolver: null,
+  resolver: undefined,
   restoreMocks: false,
   rootDir: '/test_root_dir/',
   roots: [],
@@ -102,7 +102,7 @@ const DEFAULT_PROJECT_CONFIG: Config.ProjectConfig = {
   setupFilesAfterEnv: [],
   skipFilter: false,
   skipNodeResolution: false,
-  snapshotResolver: null,
+  snapshotResolver: undefined,
   snapshotSerializers: [],
   testEnvironment: 'node',
   testEnvironmentOptions: {},
@@ -115,7 +115,7 @@ const DEFAULT_PROJECT_CONFIG: Config.ProjectConfig = {
   timers: 'real',
   transform: [],
   transformIgnorePatterns: [],
-  unmockedModulePathPatterns: null,
+  unmockedModulePathPatterns: undefined,
   watchPathIgnorePatterns: [],
 };
 
diff --git a/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap b/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap
index 6cb0bf755035..0d7a420000ea 100644
--- a/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap
+++ b/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap
@@ -13,10 +13,7 @@ exports[`prints the config object 1`] = `
     "detectOpenHandles": false,
     "errorOnDeprecated": false,
     "extraGlobals": [],
-    "filter": null,
     "forceCoverageMatch": [],
-    "globalSetup": null,
-    "globalTeardown": null,
     "globals": {},
     "haste": {},
     "moduleDirectories": [],
@@ -31,7 +28,6 @@ exports[`prints the config object 1`] = `
     "prettierPath": "prettier",
     "resetMocks": false,
     "resetModules": false,
-    "resolver": null,
     "restoreMocks": false,
     "rootDir": "/path/to/dir",
     "roots": [
@@ -42,7 +38,6 @@ exports[`prints the config object 1`] = `
     "setupFilesAfterEnv": [],
     "skipFilter": false,
     "skipNodeResolution": false,
-    "snapshotResolver": null,
     "snapshotSerializers": [],
     "testEnvironment": "node",
     "testEnvironmentOptions": {},
@@ -57,7 +52,6 @@ exports[`prints the config object 1`] = `
     "timers": "real",
     "transform": [],
     "transformIgnorePatterns": [],
-    "unmockedModulePathPatterns": null,
     "watchPathIgnorePatterns": []
   },
   "globalConfig": {
@@ -66,7 +60,6 @@ exports[`prints the config object 1`] = `
     "changedSince": "",
     "collectCoverage": false,
     "collectCoverageFrom": [],
-    "collectCoverageOnlyFrom": null,
     "coverageDirectory": "coverage",
     "coverageProvider": "babel",
     "coverageReporters": [],
@@ -75,31 +68,24 @@ exports[`prints the config object 1`] = `
     },
     "detectLeaks": false,
     "detectOpenHandles": false,
-    "enabledTestsMap": null,
     "errorOnDeprecated": false,
     "expand": false,
-    "filter": null,
     "findRelatedTests": false,
     "forceExit": false,
-    "globalSetup": null,
-    "globalTeardown": null,
     "json": false,
     "lastCommit": false,
     "listTests": false,
     "logHeapUsage": false,
     "maxConcurrency": 5,
     "maxWorkers": 2,
-    "noSCM": null,
     "noStackTrace": false,
     "nonFlagArgs": [],
     "notify": false,
     "notifyMode": "failure-change",
     "onlyChanged": false,
     "onlyFailures": false,
-    "outputFile": null,
     "passWithNoTests": false,
     "projects": [],
-    "replname": null,
     "reporters": [],
     "rootDir": "/test_root_dir/",
     "runTestsByPath": false,
@@ -108,7 +94,6 @@ exports[`prints the config object 1`] = `
     "testFailureExitCode": 1,
     "testNamePattern": "",
     "testPathPattern": "",
-    "testResultsProcessor": null,
     "testSequencer": "@jest/test-sequencer",
     "testTimeout": 5000,
     "updateSnapshot": "none",
diff --git a/packages/jest-transform/src/__tests__/__snapshots__/script_transformer.test.js.snap b/packages/jest-transform/src/__tests__/__snapshots__/script_transformer.test.js.snap
index 8cc51acac4fa..6114987506eb 100644
--- a/packages/jest-transform/src/__tests__/__snapshots__/script_transformer.test.js.snap
+++ b/packages/jest-transform/src/__tests__/__snapshots__/script_transformer.test.js.snap
@@ -14,10 +14,10 @@ Object {
     "displayName": undefined,
     "errorOnDeprecated": false,
     "extraGlobals": Array [],
-    "filter": null,
+    "filter": undefined,
     "forceCoverageMatch": Array [],
-    "globalSetup": null,
-    "globalTeardown": null,
+    "globalSetup": undefined,
+    "globalTeardown": undefined,
     "globals": Object {},
     "haste": Object {},
     "moduleDirectories": Array [],
@@ -32,7 +32,7 @@ Object {
     "prettierPath": "prettier",
     "resetMocks": false,
     "resetModules": false,
-    "resolver": null,
+    "resolver": undefined,
     "restoreMocks": false,
     "rootDir": "/",
     "roots": Array [],
@@ -41,7 +41,7 @@ Object {
     "setupFilesAfterEnv": Array [],
     "skipFilter": false,
     "skipNodeResolution": false,
-    "snapshotResolver": null,
+    "snapshotResolver": undefined,
     "snapshotSerializers": Array [],
     "testEnvironment": "node",
     "testEnvironmentOptions": Object {},
@@ -63,7 +63,7 @@ Object {
     "transformIgnorePatterns": Array [
       "/node_modules/",
     ],
-    "unmockedModulePathPatterns": null,
+    "unmockedModulePathPatterns": undefined,
     "watchPathIgnorePatterns": Array [],
   },
   "instrument": true,
@@ -229,7 +229,7 @@ exports[`ScriptTransformer uses multiple preprocessors 1`] = `
 const TRANSFORMED = {
   filename: '/fruits/banana.js',
   script: 'module.exports = "banana";',
-  config: '{"automock":false,"cache":true,"cacheDirectory":"/cache/","clearMocks":false,"coveragePathIgnorePatterns":[],"cwd":"/test_root_dir/","detectLeaks":false,"detectOpenHandles":false,"errorOnDeprecated":false,"extraGlobals":[],"filter":null,"forceCoverageMatch":[],"globalSetup":null,"globalTeardown":null,"globals":{},"haste":{},"moduleDirectories":[],"moduleFileExtensions":["js"],"moduleLoader":"/test_module_loader_path","moduleNameMapper":[],"modulePathIgnorePatterns":[],"modulePaths":[],"name":"test","prettierPath":"prettier","resetMocks":false,"resetModules":false,"resolver":null,"restoreMocks":false,"rootDir":"/","roots":[],"runner":"jest-runner","setupFiles":[],"setupFilesAfterEnv":[],"skipFilter":false,"skipNodeResolution":false,"snapshotResolver":null,"snapshotSerializers":[],"testEnvironment":"node","testEnvironmentOptions":{},"testLocationInResults":false,"testMatch":[],"testPathIgnorePatterns":[],"testRegex":["\\\\.test\\\\.js$"],"testRunner":"jest-jasmine2","testURL":"http://localhost","timers":"real","transform":[["^.+\\\\.js$","test_preprocessor"],["^.+\\\\.css$","css-preprocessor"]],"transformIgnorePatterns":["/node_modules/"],"unmockedModulePathPatterns":null,"watchPathIgnorePatterns":[]}',
+  config: '{"automock":false,"cache":true,"cacheDirectory":"/cache/","clearMocks":false,"coveragePathIgnorePatterns":[],"cwd":"/test_root_dir/","detectLeaks":false,"detectOpenHandles":false,"errorOnDeprecated":false,"extraGlobals":[],"forceCoverageMatch":[],"globals":{},"haste":{},"moduleDirectories":[],"moduleFileExtensions":["js"],"moduleLoader":"/test_module_loader_path","moduleNameMapper":[],"modulePathIgnorePatterns":[],"modulePaths":[],"name":"test","prettierPath":"prettier","resetMocks":false,"resetModules":false,"restoreMocks":false,"rootDir":"/","roots":[],"runner":"jest-runner","setupFiles":[],"setupFilesAfterEnv":[],"skipFilter":false,"skipNodeResolution":false,"snapshotSerializers":[],"testEnvironment":"node","testEnvironmentOptions":{},"testLocationInResults":false,"testMatch":[],"testPathIgnorePatterns":[],"testRegex":["\\\\.test\\\\.js$"],"testRunner":"jest-jasmine2","testURL":"http://localhost","timers":"real","transform":[["^.+\\\\.js$","test_preprocessor"],["^.+\\\\.css$","css-preprocessor"]],"transformIgnorePatterns":["/node_modules/"],"watchPathIgnorePatterns":[]}',
 };
 `;
 
@@ -246,7 +246,7 @@ exports[`ScriptTransformer uses the supplied preprocessor 1`] = `
 const TRANSFORMED = {
   filename: '/fruits/banana.js',
   script: 'module.exports = "banana";',
-  config: '{"automock":false,"cache":true,"cacheDirectory":"/cache/","clearMocks":false,"coveragePathIgnorePatterns":[],"cwd":"/test_root_dir/","detectLeaks":false,"detectOpenHandles":false,"errorOnDeprecated":false,"extraGlobals":[],"filter":null,"forceCoverageMatch":[],"globalSetup":null,"globalTeardown":null,"globals":{},"haste":{},"moduleDirectories":[],"moduleFileExtensions":["js"],"moduleLoader":"/test_module_loader_path","moduleNameMapper":[],"modulePathIgnorePatterns":[],"modulePaths":[],"name":"test","prettierPath":"prettier","resetMocks":false,"resetModules":false,"resolver":null,"restoreMocks":false,"rootDir":"/","roots":[],"runner":"jest-runner","setupFiles":[],"setupFilesAfterEnv":[],"skipFilter":false,"skipNodeResolution":false,"snapshotResolver":null,"snapshotSerializers":[],"testEnvironment":"node","testEnvironmentOptions":{},"testLocationInResults":false,"testMatch":[],"testPathIgnorePatterns":[],"testRegex":["\\\\.test\\\\.js$"],"testRunner":"jest-jasmine2","testURL":"http://localhost","timers":"real","transform":[["^.+\\\\.js$","test_preprocessor"]],"transformIgnorePatterns":["/node_modules/"],"unmockedModulePathPatterns":null,"watchPathIgnorePatterns":[]}',
+  config: '{"automock":false,"cache":true,"cacheDirectory":"/cache/","clearMocks":false,"coveragePathIgnorePatterns":[],"cwd":"/test_root_dir/","detectLeaks":false,"detectOpenHandles":false,"errorOnDeprecated":false,"extraGlobals":[],"forceCoverageMatch":[],"globals":{},"haste":{},"moduleDirectories":[],"moduleFileExtensions":["js"],"moduleLoader":"/test_module_loader_path","moduleNameMapper":[],"modulePathIgnorePatterns":[],"modulePaths":[],"name":"test","prettierPath":"prettier","resetMocks":false,"resetModules":false,"restoreMocks":false,"rootDir":"/","roots":[],"runner":"jest-runner","setupFiles":[],"setupFilesAfterEnv":[],"skipFilter":false,"skipNodeResolution":false,"snapshotSerializers":[],"testEnvironment":"node","testEnvironmentOptions":{},"testLocationInResults":false,"testMatch":[],"testPathIgnorePatterns":[],"testRegex":["\\\\.test\\\\.js$"],"testRunner":"jest-jasmine2","testURL":"http://localhost","timers":"real","transform":[["^.+\\\\.js$","test_preprocessor"]],"transformIgnorePatterns":["/node_modules/"],"watchPathIgnorePatterns":[]}',
 };
 `;