Implemented awaiting an uncaught exception

Author: Kræn Hansen

.vscode/launch.json

@@ -74,7 +74,7 @@
                 "--import=tsx",
                 "--expose_gc",
                 "--enable-source-maps",
-                "--no-warnings",
+                "--force-node-api-uncaught-exceptions-policy",
                 "${workspaceRoot}/node_modules/mocha/lib/cli/cli.js",
                 "--require",
                 "src/node/inject-dev-environment.ts",
@@ -85,6 +85,28 @@
                 "${input:integrationTestFilter}"
             ]
         },
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "LLDB: Integration tests (throwing from listeners)",
+            "program": "node",
+            "cwd": "${workspaceRoot}/integration-tests/tests",
+            "args": [
+                "--inspect",
+                "--import=tsx",
+                "--expose_gc",
+                "--enable-source-maps",
+                "--force-node-api-uncaught-exceptions-policy",
+                "${workspaceRoot}/node_modules/mocha/lib/cli/cli.js",
+                "--require",
+                "src/node/inject-dev-environment.ts",
+                "src/node/index.ts",
+                "--timeout",
+                "10000",
+                "--grep",
+                "can throw from a listener"
+            ]
+        },
         {
             "type": "node",
             "presentation": {
@@ -99,7 +121,7 @@
                 "--import=tsx",
                 "--expose_gc",
                 "--enable-source-maps",
-                "--no-warnings"
+                "--force-node-api-uncaught-exceptions-policy"
             ],
             "args": [
                 "--require",

integration-tests/environments/node/package.json

@@ -6,20 +6,20 @@
   "scripts": {
     "test": "wireit",
     "test:commonjs": "wireit",
-    "test:ci": "mocha-remote --reporter @realm/mocha-reporter -- tsx index.mjs",
+    "test:ci": "mocha-remote --reporter @realm/mocha-reporter -- tsx --force-node-api-uncaught-exceptions-policy index.mjs",
     "lint": "eslint --ext js,mjs ."
   },
   "wireit": {
     "test": {
-      "command": "mocha-remote --reporter @realm/mocha-reporter -- tsx index.mjs",
+      "command": "mocha-remote --reporter @realm/mocha-reporter -- tsx --force-node-api-uncaught-exceptions-policy index.mjs",
       "dependencies": [
         "../../../packages/realm:build:ts",
         "../../../packages/realm:build:node",
         "../../../packages/mocha-reporter:bundle"
       ]
     },
     "test:commonjs": {
-      "command": "mocha-remote --reporter @realm/mocha-reporter -- tsx index.cjs",
+      "command": "mocha-remote --reporter @realm/mocha-reporter -- tsx --force-node-api-uncaught-exceptions-policy index.cjs",
       "dependencies": [
         "../../../packages/realm:build:ts",
         "../../../packages/realm:build:node",

integration-tests/tests/.mocharc.json

@@ -3,7 +3,7 @@
     "import=tsx",
     "expose_gc",
     "enable-source-maps",
-    "no-warnings"
+    "force-node-api-uncaught-exceptions-policy"
   ],
   "reporter": "@realm/mocha-reporter",
   "require": [

integration-tests/tests/src/node/setup-globals.ts

@@ -44,6 +44,29 @@ Object.assign(globalThis, {
     },
   },
   gc: vm.runInNewContext("gc"),
+  async nextUncaughtException(timeoutMs = 5000) {
+    // Remove any other listeners, storing them later so they can be restored
+    const listenersBefore = process.listeners("uncaughtException");
+    process.removeAllListeners("uncaughtException");
+    try {
+      return await new Promise<Error>((resolve, reject) => {
+        const timeoutTimer = setTimeout(() => {
+          process.off("uncaughtException", handleException);
+          const error = new Error(`Timed out waiting for uncaught exception (waited ${timeoutMs} ms)`);
+          reject(error);
+        }, timeoutMs);
+        function handleException(error: Error) {
+          clearTimeout(timeoutTimer);
+          resolve(error);
+        }
+        process.once("uncaughtException", handleException);
+      });
+    } finally {
+      for (const listener of listenersBefore) {
+        process.addListener("uncaughtException", listener);
+      }
+    }
+  },
 });
 
 // Indicate that the tests are running in Node

integration-tests/tests/src/tests/observable.ts

@@ -467,12 +467,16 @@ describe("Observable", () => {
     });
 
     it.skipIf(
-      !environment.testThrowingListeners,
+      typeof nextUncaughtException !== "function",
       "can throw from a listener",
       async function (this: RealmObjectContext<Person>) {
+        assert(typeof nextUncaughtException === "function", "Expected ability to await an uncaught exception");
+        const uncaughtException = nextUncaughtException();
         this.object.addListener(() => {
           throw new Error("boom!");
         });
+        const error = await uncaughtException;
+        expect(error.message).equals("boom!");
       },
     );
 
@@ -880,12 +884,16 @@ describe("Observable", () => {
     });
 
     it.skipIf(
-      !environment.testThrowingListeners,
+      typeof nextUncaughtException !== "function",
       "can throw from a listener",
       async function (this: RealmObjectContext<Person>) {
+        assert(typeof nextUncaughtException === "function", "Expected ability to await an uncaught exception");
+        const uncaughtException = nextUncaughtException();
         this.realm.objects("Person").addListener(() => {
           throw new Error("boom!");
         });
+        const error = await uncaughtException;
+        expect(error.message).equals("boom!");
       },
     );
 

integration-tests/tests/src/typings.d.ts

@@ -107,12 +107,6 @@ type KnownEnvironment = {
    * React native specific variable injected by the runner, to signal if the tests are ran by the legacy chrome debugger (i.e. in a browser).
    * @deprecated Since we no longer support the legacy chrome debugger. */
   chromeDebugging?: true;
-
-  /**
-   * Test throwing from listeners.
-   * These tests are skipped by default, because we don't want these to fail and we don't have a good way to instrument Mocha to expect these uncaught exceptions.
-   */
-  testThrowingListeners?: true;
 };
 
 type Environment = KnownEnvironment & Record<string, unknown>;
@@ -122,6 +116,7 @@ declare const fs: fs;
 declare const path: path;
 declare const environment: Environment;
 declare const gc: undefined | (() => void);
+declare const nextUncaughtException: undefined | (() => Promise<Error>);
 
 // Extend the mocha test function with the skipIf that we patch in from index.ts
 declare namespace Mocha {