error in haste map as well and add tests verifying it

e2e/__tests__/crawlSymlinks.test.ts

@@ -74,10 +74,15 @@ test('Node crawler does not pick up symlinked files by default', () => {
 test('Should throw if watchman used with haste.enableSymlinks', () => {
   init({'.watchmanconfig': JSON.stringify({})});
 
-  const {stdout, stderr, exitCode} = runJest(DIR, [
-    '--haste={"enableSymlinks": true}',
-    '--watchman',
-  ]);
+  // it should throw both if watchman is explicitly provided and not
+  const run1 = runJest(DIR, ['--haste={"enableSymlinks": true}']);
+  const run2 = runJest(DIR, ['--haste={"enableSymlinks": true}', '--watchman']);
+
+  expect(run1.exitCode).toEqual(run2.exitCode);
+  expect(run1.stderr).toEqual(run2.stderr);
+  expect(run1.stdout).toEqual(run2.stdout);
+
+  const {exitCode, stderr, stdout} = run1;
 
   expect(stdout).toEqual('');
   expect(wrap(stderr)).toMatchInlineSnapshot(`

packages/jest-config/src/__tests__/normalize.test.js

@@ -1714,3 +1714,26 @@ describe('testTimeout', () => {
     ).toThrowErrorMatchingSnapshot();
   });
 });
+
+describe('haste.enableSymlinks', () => {
+  it('should throw if watchman is not disabled', () => {
+    expect(() =>
+      normalize({haste: {enableSymlinks: true}, rootDir: '/root/'}, {}),
+    ).toThrow('haste.enableSymlinks is incompatible with watchman');
+
+    expect(() =>
+      normalize(
+        {haste: {enableSymlinks: true}, rootDir: '/root/', watchman: true},
+        {},
+      ),
+    ).toThrow('haste.enableSymlinks is incompatible with watchman');
+
+    const {options} = normalize(
+      {haste: {enableSymlinks: true}, rootDir: '/root/', watchman: false},
+      {},
+    );
+
+    expect(options.haste.enableSymlinks).toBe(true);
+    expect(options.watchman).toBe(false);
+  });
+});

packages/jest-config/src/normalize.ts

@@ -577,6 +577,10 @@ export default function normalize(
     });
   }
 
+  if (options.watchman == null) {
+    options.watchman = DEFAULT_CONFIG.watchman;
+  }
+
   const optionKeys = Object.keys(options) as Array<keyof Config.InitialOptions>;
 
   optionKeys.reduce((newOptions, key: keyof Config.InitialOptions) => {

packages/jest-haste-map/src/__tests__/index.test.js

@@ -517,6 +517,29 @@ describe('HasteMap', () => {
     });
   });
 
+  it('throws if both symlinks and watchman is enabled', () => {
+    expect(
+      () => new HasteMap({...defaultConfig, enableSymlinks: true}),
+    ).toThrow('Set either `enableSymlinks` to false or `watchman` to false.');
+    expect(
+      () =>
+        new HasteMap({
+          ...defaultConfig,
+          enableSymlinks: true,
+          useWatchman: true,
+        }),
+    ).toThrow('Set either `enableSymlinks` to false or `watchman` to false.');
+
+    expect(
+      () =>
+        new HasteMap({
+          ...defaultConfig,
+          enableSymlinks: true,
+          useWatchman: false,
+        }),
+    ).not.toThrow();
+  });
+
   describe('builds a haste map on a fresh cache with SHA-1s', () => {
     [false, true].forEach(useWatchman => {
       it('uses watchman: ' + useWatchman, async () => {

packages/jest-haste-map/src/index.ts

@@ -282,7 +282,7 @@ class HasteMap extends EventEmitter {
       throw new Error(
         'jest-haste-map: enableSymlinks config option was set, but ' +
           'is incompatible with watchman.\n' +
-          'Set either `enableSymlinks` to false or `watchman` to false ',
+          'Set either `enableSymlinks` to false or `watchman` to false.',
       );
     }