fix(core): add keepExistingVersions to jest option to preserve dependency versions (#30652)

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## Current Behavior
<!-- This is the behavior we have today -->
Currently, when we use the jest configuration generator it will forcibly
update the jest version if the package already exist.


## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->
Now, the jest version will be preserved unless the option is passed to
update the version.

## Related Issue(s)
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merged. -->

Fixes #

docs/generated/packages/jest/generators/configuration.json

@@ -79,6 +79,12 @@
       "runtimeTsconfigFileName": {
         "type": "string",
         "description": "The name of the project's tsconfig file that includes the runtime source files. If not provided, it will default to `tsconfig.lib.json` for libraries and `tsconfig.app.json` for applications."
+      },
+      "keepExistingVersions": {
+        "type": "boolean",
+        "x-priority": "internal",
+        "description": "Keep existing dependencies versions",
+        "default": true
       }
     },
     "required": [],

e2e/js/src/js-generators.ts

@@ -2,12 +2,15 @@ import {
   checkFilesDoNotExist,
   checkFilesExist,
   cleanupProject,
+  detectPackageManager,
+  getPackageManagerCommand,
   newProject,
   readFile,
   readJson,
   rmDist,
   runCLI,
   runCLIAsync,
+  runCommand,
   uniq,
   updateFile,
   updateJson,
@@ -187,4 +190,23 @@ describe('js e2e', () => {
       'Test Suites: 1 passed, 1 total'
     );
   }, 500_000);
+
+  it('should not update dependencies if they already exist', () => {
+    const lib = uniq('@my-org/mylib');
+    const currentJestVersion = '28.0.0';
+    const pm = detectPackageManager();
+    // set jest version
+    updateJson('package.json', (json) => {
+      json.devDependencies['jest'] = currentJestVersion;
+      return json;
+    });
+
+    runCommand(getPackageManagerCommand({ packageManager: pm }).install);
+
+    runCLI(`generate @nx/js:lib ${lib} --bundler=tsc --unitTestRunner=jest`);
+
+    const jestVersionAfterInstall =
+      readJson('package.json').devDependencies['jest'];
+    expect(jestVersionAfterInstall).toEqual(currentJestVersion);
+  });
 });

packages/jest/src/generators/configuration/configuration.ts

@@ -71,6 +71,7 @@ function normalizeOptions(
   return {
     ...schemaDefaults,
     ...options,
+    keepExistingVersions: options.keepExistingVersions ?? true,
     rootProject: project.root === '.' || project.root === '',
     isTsSolutionSetup: isUsingTsSolutionSetup(tree),
   };

packages/jest/src/generators/configuration/lib/ensure-dependencies.ts

@@ -44,5 +44,11 @@ export function ensureDependencies(
     devDeps['@swc/jest'] = swcJestVersion;
   }
 
-  return addDependenciesToPackageJson(tree, dependencies, devDeps);
+  return addDependenciesToPackageJson(
+    tree,
+    dependencies,
+    devDeps,
+    undefined,
+    options.keepExistingVersions
+  );
 }

packages/jest/src/generators/configuration/schema.d.ts

@@ -30,6 +30,7 @@ export interface JestProjectSchema {
    * @deprecated Use the `setupFile` option instead. It will be removed in Nx v22.
    */
   skipSetupFile?: boolean;
+  keepExistingVersions?: boolean;
 }
 
 export type NormalizedJestProjectSchema = JestProjectSchema & {

packages/jest/src/generators/configuration/schema.json

@@ -78,6 +78,12 @@
     "runtimeTsconfigFileName": {
       "type": "string",
       "description": "The name of the project's tsconfig file that includes the runtime source files. If not provided, it will default to `tsconfig.lib.json` for libraries and `tsconfig.app.json` for applications."
+    },
+    "keepExistingVersions": {
+      "type": "boolean",
+      "x-priority": "internal",
+      "description": "Keep existing dependencies versions",
+      "default": true
     }
   },
   "required": []