Fix #2291 by documenting how to debug TS tests (#2306)

.vscode/launch.json

@@ -3,20 +3,29 @@
     "configurations": [
         {
             "type": "node",
-            "request": "launch",
-            "name": "Launch Program",
-            "program": "${workspaceRoot}/client-ts/node_modules/jasmine/bin/jasmine.js",
-            "args": ["JASMINE_CONFIG_PATH=${workspaceRoot}/client-ts/Microsoft.AspNetCore.SignalR.Client.TS.Tests/jasmine.json"],
-            "cwd": "${workspaceRoot}/client-ts",
-            "outFiles": []
+            "request": "attach",
+            "name": "Node - Attach by Process ID",
+            "processId": "${command:PickProcess}"
         },
         {
             "type": "node",
-            "request": "attach",
-            "name": "Attach to Port",
-            "address": "localhost",
-            "port": 5858,
-            "outFiles": []
-        }
+            "request": "launch",
+            "name": "Jest - All",
+            "program": "${workspaceFolder}/clients/ts/node_modules/jest/bin/jest",
+            "cwd": "${workspaceFolder}/clients/ts",
+            "args": ["--runInBand"],
+            "console": "integratedTerminal",
+            "internalConsoleOptions": "neverOpen"
+          },
+          {
+            "type": "node",
+            "request": "launch",
+            "name": "Jest - Current File",
+            "program": "${workspaceFolder}/clients/ts/node_modules/jest/bin/jest",
+            "cwd": "${workspaceFolder}/clients/ts",
+            "args": ["${relativeFile}"],
+            "console": "integratedTerminal",
+            "internalConsoleOptions": "neverOpen"
+          }
     ]
 }

clients/ts/DebuggingTests.md

@@ -0,0 +1,94 @@
+# Debugging/Running Jest Tests
+
+We use [Jest](https://facebook.github.io/jest/) as our JavaScript testing framework. We also use [ts-jest](https://github.com/kulshekhar/ts-jest) which builds TypeScript automatically.
+
+Prerequisites: NodeJS, have run `./build.cmd /t:Restore` at least once since cleaning.
+
+All commands must be run from this directory (the `clients/ts` directory).
+
+## Running all tests
+
+```
+> npm test
+```
+
+## Running all tests in a specific file
+
+```
+> npm test -- FileName
+```
+
+`FileName` can be a substring of the path, it will run all test files containing that **substring** in the path.
+
+For example (use `/` for paths even on Windows, since Node is interpreting them):
+
+* `npm test -- signalr/tests` will run all tests in `clients\ts\signalr\tests`
+* `npm test -- signalr-protocol-msgpack/tests` will run all tests in `clients\ts\signalr-protocol-msgpack\tests`
+* `npm test -- signalr/tests/` will run all tests in `clients\ts\signalr\tests`
+* `npm test -- signalr/tests/JsonHubProtocol` will run all tests in `signalr/tests/JsonHubProtocol.test.ts`
+* `npm test -- JsonHubProtocol` will **also** run all tests in `signalr/tests/JsonHubProtocol.test.ts` because it's the only test file matching that pattern
+
+## Running a single test
+
+The simplest way to run a single test is to use `.only`. Marking a test with `.only` will ensure that **only** that test is run when running tests from that file. If you are running multiple files (i.e. `npm test` with no arguments, it will still run all the tests in the other files).
+
+To use `.only`, just add `.only` to the end of the call to `it`:
+
+```typescript
+describe("A suite of tests", () => {
+    describe("A sub-suite of tests", () => {
+        it.only("will run", () => {
+
+        });
+
+        it("will not run", () => {
+
+        });
+    });
+
+    describe("Another sub-suite of tests", () => {
+        it("will not run either", () => {
+
+        });
+    });
+});
+```
+
+Just make sure you remove `.only` when you finish running that test!
+
+You can also use the `-t` parameter to jest. That parameter takes a substring pattern to match against all tests to see if they should run. To improve the speed of the run, you should pair this up with the argument that takes a file path to filter on. For example, given these tests
+
+```
+describe("AbortSignal", () => {
+    describe("aborted", () => {
+        it("is false on initialization", () => {
+            // ...
+        });
+
+        it("is true when aborted", () => {
+            // ...
+        });
+    });
+
+    describe("onabort", () => {
+        it("is called when abort is called", () => {
+            // ...
+        });
+    });
+});
+```
+
+These commands will each run the following sets of tests:
+
+* `npm test -- AbortSignal -t "AbortSignal aborted"` will run `AbortSignal aborted is false on initialization` and `AbortSignal aborted is true when aborted`.
+* `npm test -- AbortSignal -t "is called when abort is called"` will run `AbortSignal onabort is called when abort is called`.
+
+## Debugging All Tests
+
+You can launch all tests under the debugger in Visual Studio Code by clicking on the "Debug" tab on the left side, selecting "Jest - All" in the dropdown at the top and clicking the play button, or pressing F5.
+
+## Debugging All Tests in a single file
+
+You can launch all tests **in the currently open file** under the debugger in Visual Studio Code by clicking on the "Debug" tab on the left side, selecting "Jest - Current File" in the dropdown at the top and clicking the play button, or pressing F5.
+
+**NOTE**: Pair this with `.only` to easily debug a single test!