From c7f845b017a492116a1bc2f2aaa6325b68193e79 Mon Sep 17 00:00:00 2001
From: Juri <juri.strumpflohner@gmail.com>
Date: Fri, 17 Jan 2020 12:03:47 +0100
Subject: [PATCH] fix(misc): update package.json only if needed

Adjusts the schematic to only touch the package.json if really required

ISSUES CLOSED: #2317
---
 packages/jest/src/schematics/init/init.ts | 107 ++++++++++++++++++----
 1 file changed, 89 insertions(+), 18 deletions(-)

diff --git a/packages/jest/src/schematics/init/init.ts b/packages/jest/src/schematics/init/init.ts
index 8fb9cdfb5fa89b..8a9ec58378b600 100644
--- a/packages/jest/src/schematics/init/init.ts
+++ b/packages/jest/src/schematics/init/init.ts
@@ -1,5 +1,9 @@
 import { mergeWith, chain, url, Tree } from '@angular-devkit/schematics';
-import { addDepsToPackageJson, updateJsonInTree } from '@nrwl/workspace';
+import {
+  addDepsToPackageJson,
+  updateJsonInTree,
+  readJsonInTree
+} from '@nrwl/workspace';
 import {
   jestVersion,
   jestTypesVersion,
@@ -9,22 +13,89 @@ import {
 import { Rule } from '@angular-devkit/schematics';
 import { stripIndents } from '@angular-devkit/core/src/utils/literals';
 
-const updatePackageJson = chain([
-  addDepsToPackageJson(
-    {},
-    {
-      '@nrwl/jest': nxVersion,
-      jest: jestVersion,
-      '@types/jest': jestTypesVersion,
-      'ts-jest': tsJestVersion
-    }
-  ),
-  updateJsonInTree('package.json', json => {
-    json.dependencies = json.dependencies || {};
-    delete json.dependencies['@nrwl/jest'];
-    return json;
-  })
-]);
+/**
+ * verifies whether the given packageJson dependencies require an update
+ * given the deps & devDeps passed in
+ */
+const requiresAddingOfPackages = (packageJsonFile, deps, devDeps): boolean => {
+  let needsDepsUpdate = false;
+  let needsDevDepsUpdate = false;
+
+  if (Object.keys(deps).length > 0 && packageJsonFile.dependencies) {
+    needsDepsUpdate = !Object.keys(deps).find(
+      entry => packageJsonFile.dependencies[entry]
+    );
+  }
+
+  if (Object.keys(devDeps).length > 0 && packageJsonFile.dependencies) {
+    needsDevDepsUpdate = !Object.keys(devDeps).find(
+      entry => packageJsonFile.devDependencies[entry]
+    );
+  }
+
+  return needsDepsUpdate || needsDevDepsUpdate;
+};
+
+const updatePackageJson = (host: Tree): Rule => {
+  const rules = [];
+
+  // check whether to update the packge.json is necessary
+  const currentPackageJson = readJsonInTree(host, 'package.json');
+  const devDepstoUpdate = {
+    '@nrwl/jest': nxVersion,
+    jest: jestVersion,
+    '@types/jest': jestTypesVersion,
+    'ts-jest': tsJestVersion
+  };
+
+  if (requiresAddingOfPackages(currentPackageJson, {}, devDepstoUpdate)) {
+    rules.push(
+      addDepsToPackageJson(
+        {},
+        {
+          '@nrwl/jest': nxVersion,
+          jest: jestVersion,
+          '@types/jest': jestTypesVersion,
+          'ts-jest': tsJestVersion
+        }
+      )
+    );
+  }
+
+  if (
+    currentPackageJson.dependencies &&
+    currentPackageJson.dependencies['@nrwl/jest']
+  ) {
+    rules.push(
+      updateJsonInTree('package.json', json => {
+        json.dependencies = json.dependencies || {};
+        delete json.dependencies['@nrwl/jest'];
+        return json;
+      })
+    );
+  }
+
+  return chain(rules);
+};
+
+const updatePackageJson2 = () => {
+  return chain([
+    addDepsToPackageJson(
+      {},
+      {
+        '@nrwl/jest': nxVersion,
+        jest: jestVersion,
+        '@types/jest': jestTypesVersion,
+        'ts-jest': tsJestVersion
+      }
+    ),
+    updateJsonInTree('package.json', json => {
+      json.dependencies = json.dependencies || {};
+      delete json.dependencies['@nrwl/jest'];
+      return json;
+    })
+  ]);
+};
 
 const createJestConfig = (host: Tree) => {
   if (!host.exists('jest.config.js')) {
@@ -46,5 +117,5 @@ const createJestConfig = (host: Tree) => {
 };
 
 export default function(): Rule {
-  return chain([createJestConfig, updatePackageJson]);
+  return chain([createJestConfig, updatePackageJson2]);
 }