fix(jest): warn with a helpful warning when unable to update the config

packages/jest/src/utils/config/functions.ts

@@ -160,10 +160,6 @@ export function jestConfigObjectAst(
   host: Tree,
   path: string
 ): ts.ObjectLiteralExpression {
-  if (!host.exists(path)) {
-    throw new Error(`Cannot find '${path}' in your workspace.`);
-  }
-
   const fileContent = host.read(path).toString('utf-8');
 
   const sourceFile = ts.createSourceFile(
@@ -181,8 +177,7 @@ export function jestConfigObjectAst(
   const moduleExports = expressions.find(
     (node) =>
       node.left.getText() === 'module.exports' &&
-      node.operatorToken.kind === ts.SyntaxKind.EqualsToken &&
+      node.operatorToken.kind === ts.SyntaxKind.EqualsToken
-      ts.isObjectLiteralExpression(node.right)
   );
 
   if (!moduleExports) {
@@ -193,6 +188,12 @@ export function jestConfigObjectAst(
     );
   }
 
+  if (!ts.isObjectLiteralExpression(moduleExports.right)) {
+    throw new Error(
+      `The 'module.exports' expression is not an object literal.`
+    );
+  }
+
   return moduleExports.right as ts.ObjectLiteralExpression;
 }
 

packages/jest/src/utils/config/update-config.spec.ts

@@ -164,19 +164,22 @@ describe('Update jest.config.js', () => {
       expect(json['update-me']).toEqual('goodbye');
     });
 
-    describe('errors', () => {
+    describe('warnings', () => {
-      it('should throw an error when trying to add a value to an already existing object without being dot delimited', () => {
+      beforeEach(() => {
-        expect(() => {
+        spyOn(console, 'warn').and.callThrough();
+      });
+
+      it('should warn when trying to add a value to an already existing object without being dot delimited', () => {
         addPropertyToJestConfig(
           host,
           'jest.config.js',
           'alreadyExistingObject',
           'should fail'
         );
-        }).toThrow();
+        expect(console.warn).toHaveBeenCalled();
       });
 
-      it('should throw an error if the jest.config doesnt match module.exports = {} style', () => {
+      it('should warn if the jest.config doesnt match module.exports = {} style', () => {
         host.create(
           'jest.unconventional.js',
           String.raw`
@@ -187,14 +190,13 @@ describe('Update jest.config.js', () => {
           module.exports = jestObject;
         `
         );
-        expect(() => {
         addPropertyToJestConfig(
           host,
           'jest.unconventional.js',
           'stuffhere',
           'should fail'
         );
-        }).toThrow();
+        expect(console.warn).toHaveBeenCalled();
       });
 
       it('should throw if the provided config does not exist in the tree', () => {

packages/jest/src/utils/config/update-config.ts

@@ -19,6 +19,10 @@ export function addPropertyToJestConfig(
   propertyName: string,
   value: unknown
 ) {
+  if (!host.exists(path)) {
+    throw new Error(`Cannot find '${path}' in your workspace.`);
+  }
+  try {
     const configObject = jestConfigObjectAst(host, path);
     const properties = propertyName.split('.');
     const changes = addOrUpdateProperty(
@@ -28,6 +32,14 @@ export function addPropertyToJestConfig(
       path
     );
     insert(host, path, changes);
+  } catch (e) {
+    console.warn(
+      `Could not automatically add the following property to ${path}:`
+    );
+    console.warn(`${propertyName}: ${JSON.stringify(value)}`);
+    console.log(`Please manually update ${path}`);
+    console.warn(`Error: ${e.message}`);
+  }
 }
 
 /**
@@ -41,6 +53,10 @@ export function removePropertyFromJestConfig(
   path: string,
   propertyName: string
 ) {
+  if (!host.exists(path)) {
+    throw new Error(`Cannot find '${path}' in your workspace.`);
+  }
+  try {
     const configObject = jestConfigObjectAst(host, path);
     const propertyAssignment = removeProperty(
       configObject,
@@ -58,4 +74,10 @@ export function removePropertyFromJestConfig(
         ),
       ]);
     }
+  } catch (e) {
+    console.warn(
+      `Could not automatically remove the '${propertyName}' property from ${path}:`
+    );
+    console.log(`Please manually update ${path}`);
+  }
 }