do not modify global types via declarations

packages/jest-circus/src/legacy-code-todo-rewrite/jestAdapterInit.ts

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {Circus, Config} from '@jest/types';
+import {Circus, Config, Global} from '@jest/types';
 import {JestEnvironment} from '@jest/environment';
 import {AssertionResult, Status, TestResult} from '@jest/test-result';
 import {extractExpectedAssertionsErrors, getState, setState} from 'expect';
@@ -53,15 +53,16 @@ export const initialize = ({
 
   const mutex = throat(globalConfig.maxConcurrency);
 
-  Object.assign(global, globals);
+  const nodeGlobal = global as Global.Global;
+  Object.assign(nodeGlobal, globals);
 
-  global.xit = global.it.skip;
-  global.xtest = global.it.skip;
-  global.xdescribe = global.describe.skip;
-  global.fit = global.it.only;
-  global.fdescribe = global.describe.only;
+  nodeGlobal.xit = nodeGlobal.it.skip;
+  nodeGlobal.xtest = nodeGlobal.it.skip;
+  nodeGlobal.xdescribe = nodeGlobal.describe.skip;
+  nodeGlobal.fit = nodeGlobal.it.only;
+  nodeGlobal.fdescribe = nodeGlobal.describe.only;
 
-  global.test.concurrent = (test => {
+  nodeGlobal.test.concurrent = (test => {
     const concurrent = (
       testName: string,
       testFn: () => Promise<any>,
@@ -74,7 +75,7 @@ export const initialize = ({
       // that will result in this test to be skipped, so we'll be executing the promise function anyway,
       // even if it ends up being skipped.
       const promise = mutex(() => testFn());
-      global.test(testName, () => promise, timeout);
+      nodeGlobal.test(testName, () => promise, timeout);
     };
 
     concurrent.only = (
@@ -90,7 +91,7 @@ export const initialize = ({
     concurrent.skip = test.skip;
 
     return concurrent;
-  })(global.test);
+  })(nodeGlobal.test);
 
   addEventHandler(eventHandler);
 

packages/jest-each/src/index.ts

@@ -9,8 +9,7 @@
 import {Global} from '@jest/types';
 import bind from './bind';
 
-type Global = NodeJS.Global;
-
+type Global = Global.Global;
 const install = (
   g: Global,
   table: Global.EachTable,
@@ -44,7 +43,7 @@ const install = (
 };
 
 const each = (table: Global.EachTable, ...data: Global.TemplateData) =>
-  install(global, table, ...data);
+  install(global as Global, table, ...data);
 
 each.withGlobal = (g: Global) => (
   table: Global.EachTable,

packages/jest-jasmine2/src/jestExpect.ts

@@ -6,6 +6,7 @@
  */
 
 import expect, {MatcherState} from 'expect';
+import {Global} from '@jest/types';
 import {
   addSerializer,
   toMatchSnapshot,
@@ -15,6 +16,8 @@ import {
 } from 'jest-snapshot';
 import {RawMatcherFn, Jasmine} from './types';
 
+declare const global: Global.Global;
+
 type JasmineMatcher = {
   (matchersUtil: any, context: any): JasmineMatcher;
   compare: () => RawMatcherFn;

packages/jest-jasmine2/src/setup_jest_globals.ts

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {Config} from '@jest/types';
+import {Config, Global} from '@jest/types';
 import {Plugin} from 'pretty-format';
 import {extractExpectedAssertionsErrors, getState, setState} from 'expect';
 import {
@@ -16,6 +16,8 @@ import {
 import JasmineSpec, {Attributes, SpecResult} from './jasmine/Spec';
 import {Jasmine} from './types';
 
+declare const global: Global.Global;
+
 export type SetupOptions = {
   config: Config.ProjectConfig;
   globalConfig: Config.GlobalConfig;

packages/jest-types/src/Global.ts

@@ -83,19 +83,3 @@ export interface Global extends NodeJS.Global {
   spyOn: () => void;
   spyOnProperty: () => void;
 }
-
-declare global {
-  module NodeJS {
-    interface Global {
-      it: It;
-      test: ItConcurrent;
-      fit: ItBase;
-      xit: ItBase;
-      xtest: ItBase;
-      describe: Describe;
-      xdescribe: DescribeBase;
-      fdescribe: DescribeBase;
-      jasmine: Jasmine;
-    }
-  }
-}