fix: polling usage in watchFiles option

lib/Server.js

@@ -973,9 +973,15 @@ class Server {
     // https://github.com/webpack/watchpack/blob/master/lib/DirectoryWatcher.js#L49
     // this isn't an elegant solution, but we'll improve it in the future
     // eslint-disable-next-line no-undefined
-    const usePolling = watchOptions.poll ? true : undefined;
+    const usePolling =
+      typeof watchOptions.usePolling !== 'undefined'
+        ? watchOptions.usePolling
+        : Boolean(watchOptions.poll);
     const interval =
-      typeof watchOptions.poll === 'number'
+      // eslint-disable-next-line no-nested-ternary
+      typeof watchOptions.interval !== 'undefined'
+        ? watchOptions.interval
+        : typeof watchOptions.poll === 'number'
         ? watchOptions.poll
         : // eslint-disable-next-line no-undefined
           undefined;

test/server/__snapshots__/watchFiles-option.test.js.snap.webpack4

@@ -0,0 +1,85 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`'watchFiles' option should work with options {"poll":200} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": 200,
+  "persistent": true,
+  "usePolling": true,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"poll":true} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": true,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":false,"poll":true} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": false,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":false} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": false,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":true,"interval":200,"poll":400} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": 200,
+  "persistent": true,
+  "usePolling": true,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":true} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": true,
+}
+`;

test/server/__snapshots__/watchFiles-option.test.js.snap.webpack5

@@ -0,0 +1,85 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`'watchFiles' option should work with options {"poll":200} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": 200,
+  "persistent": true,
+  "usePolling": true,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"poll":true} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": true,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":false,"poll":true} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": false,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":false} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": false,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":true,"interval":200,"poll":400} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": 200,
+  "persistent": true,
+  "usePolling": true,
+}
+`;
+
+exports[`'watchFiles' option should work with options {"usePolling":true} should pass correct options to chokidar config 1`] = `
+Object {
+  "alwaysStat": true,
+  "atomic": false,
+  "followSymlinks": false,
+  "ignoreInitial": true,
+  "ignorePermissionErrors": true,
+  "ignored": undefined,
+  "interval": undefined,
+  "persistent": true,
+  "usePolling": true,
+}
+`;

test/server/watchFiles-option.test.js

@@ -2,6 +2,7 @@
 
 const path = require('path');
 const fs = require('graceful-fs');
+const chokidar = require('chokidar');
 const testServer = require('../helpers/test-server');
 const config = require('../fixtures/contentbase-config/webpack.config');
 const port = require('../ports-map')['watchFiles-option'];
@@ -277,38 +278,71 @@ describe("'watchFiles' option", () => {
   describe('should work with options', () => {
     const file = path.join(watchDir, 'assets/example.txt');
 
-    beforeAll((done) => {
-      server = testServer.start(
-        config,
-        {
-          watchFiles: {
-            paths: file,
-            options: {
-              usePolling: true,
+    const chokidarMock = jest.spyOn(chokidar, 'watch');
+
+    const optionCases = [
+      {
+        poll: true,
+      },
+      {
+        poll: 200,
+      },
+      {
+        usePolling: true,
+      },
+      {
+        usePolling: false,
+      },
+      {
+        usePolling: false,
+        poll: true,
+      },
+      {
+        usePolling: true,
+        interval: 200,
+        poll: 400,
+      },
+    ];
+
+    optionCases.forEach((optionCase) => {
+      describe(JSON.stringify(optionCase), () => {
+        beforeAll((done) => {
+          chokidarMock.mockClear();
+          server = testServer.start(
+            config,
+            {
+              watchFiles: {
+                paths: file,
+                options: optionCase,
+              },
+              port,
             },
-          },
-          port,
-        },
-        done
-      );
-    });
-
-    afterAll((done) => {
-      testServer.close(done);
-      fs.truncateSync(file);
-    });
-
-    it('should reload on file content changed', (done) => {
-      server.staticWatchers[0].on('change', (changedPath) => {
-        expect(changedPath).toBe(file);
-
-        done();
+            done
+          );
+        });
+
+        afterAll((done) => {
+          testServer.close(done);
+          fs.truncateSync(file);
+        });
+
+        it('should pass correct options to chokidar config', () => {
+          expect(chokidarMock.mock.calls[0][1]).toMatchSnapshot();
+        });
+
+        it('should reload on file content changed', (done) => {
+          server.staticWatchers[0].on('change', (changedPath) => {
+            expect(changedPath).toBe(file);
+
+            done();
+          });
+
+          // change file content
+          setTimeout(() => {
+            fs.writeFileSync(file, 'Kurosaki Ichigo', 'utf8');
+          }, 1000);
+        });
       });
-
-      // change file content
-      setTimeout(() => {
-        fs.writeFileSync(file, 'Kurosaki Ichigo', 'utf8');
-      }, 1000);
     });
   });
 });