test: add test for issue 1813

internal/linker/test/issue_1813/BUILD.bazel

@@ -0,0 +1,18 @@
+load("@npm//jest-cli:index.bzl", "jest_test")
+
+jest_test(
+    name = "test",
+    args = [
+        "--config",
+        "$(rootpath jest.config.js)",
+        "--runTestsByPath",
+        "$(rootpath index.test.js)",
+    ],
+    data = [
+        "index.test.js",
+        "jest.config.js",
+        "@npm//jest",
+        "@npm//jest-websocket-mock",
+        "@npm//mock-socket",
+    ],
+)

internal/linker/test/issue_1813/index.test.js

@@ -0,0 +1,13 @@
+// Loaded from common-js format
+// node_modules/jest-websocket-mock/lib/jest-websocket-mock.cjs.js
+const WS = require('jest-websocket-mock').default;
+// Loaded from js format
+// node_modules/mock-socket/dist/mock-socket.js"
+const Server = require('mock-socket').Server;
+
+test('jest-websocket-mock', () => {
+  const ws = new WS('ws://localhost:1234');
+  console.log(ws.server.constructor);        // [Function: Server] { of: [Function: of] }
+  console.log(Server);                       // [Function: Server] { of: [Function: of] }
+  expect(ws.server).toBeInstanceOf(Server);  // FAILS
+});

package.json

@@ -43,6 +43,8 @@
         "jasmine": "~3.4.0",
         "jasmine-core": "~3.4.0",
         "jasmine-reporters": "~2.3.2",
+        "jest": "~25.3.0",
+        "jest-websocket-mock": "~2.0.2",
         "karma": "~4.1.0",
         "karma-chrome-launcher": "2.2.0",
         "karma-firefox-launcher": "1.1.0",
@@ -51,6 +53,7 @@
         "karma-sourcemap-loader": "0.3.7",
         "lit-element": "^2.2.1",
         "minimist": "^1.2.2",
+        "mock-socket": "~9.0.3",
         "node_resolve_index": "file:./tools/npm_packages/node_resolve_index",
         "node_resolve_index_2": "file:./tools/npm_packages/node_resolve_index_2",
         "node_resolve_index_3": "file:./tools/npm_packages/node_resolve_index_3",