Expected / actual diff is not show if expected undefined

[jimmyn]

Describe the bug

When expecting a value to be undefined but receiving an object, the diff view is not showing, so it is impossible to see what the object contains

If compared to some defined value, it does work correctly

Reproduction

Can be reproduced with the following test:

import {expect, test} from "vitest";

test('demo', () => {
  const error = {
    message: 'Some very long error message',
  }
  expect(error).toBeUndefined();
});

Output

[INFO 18:10:42] [v1.2.17] Vitest extension is activated because Vitest is installed or there is a Vite/Vitest config file in the workspace.
[INFO 18:10:42] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:10:42] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19446 created
[INFO 18:10:43] [API] Collecting tests: demo.test.ts
[18:10:43] Not starting the runner because tests are being collected
[18:10:43] There is no test run for "demo.test.ts"
[18:10:43] No test run to finish for demo.test.ts
[INFO 18:10:46] Running 1 file(s) with name pattern: ^\s?demo$
[18:10:46] The runner is starting because tests demo.test.ts were started due to a file change
[18:10:46] Enqueuing "demo"
[18:10:46] No task result for "demo", assuming the test just started running
[18:10:46] Marking "demo" as passed
[18:10:46] Ending test run demo.test.ts
[INFO 18:10:50] Running 1 file(s) with name pattern: ^\s?demo$
[18:10:50] The runner is starting because tests demo.test.ts were started due to a file change
[18:10:50] Enqueuing "demo"
[18:10:50] No task result for "demo", assuming the test just started running
[18:10:50] Marking "demo" as passed
[18:10:50] Ending test run demo.test.ts
[INFO 18:10:50] Running 1 file(s) with name pattern: ^\s?demo$
[18:10:50] The runner is starting because tests demo.test.ts were started due to a file change
[18:10:50] Enqueuing "demo"
[18:10:50] No task result for "demo", assuming the test just started running
[18:10:50] Marking "demo" as passed
[18:10:50] Ending test run demo.test.ts
[INFO 18:10:53] Running 1 file(s) with name pattern: ^\s?demo$
[18:10:53] The runner is starting because tests demo.test.ts were started due to a file change
[18:10:53] Enqueuing "demo"
[18:10:54] No task result for "demo", assuming the test just started running
[18:10:54] Marking "demo" as passed
[18:10:54] Ending test run demo.test.ts
[INFO 18:10:56] [API] Vitest process 19446 closed successfully
[INFO 18:10:56] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:10:56] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19508 created
[INFO 18:10:56] [API] Collecting tests: demo.test.ts
[18:10:56] Not starting the runner because tests are being collected
[18:10:56] There is no test run for "demo.test.ts"
[18:10:56] No test run to finish for demo.test.ts
[INFO 18:10:57] Running 1 file(s) with name pattern: ^\s?demo$
[18:10:57] The runner is starting because tests demo.test.ts were started due to a file change
[18:10:57] Enqueuing "demo"
[18:10:57] No task result for "demo", assuming the test just started running
[18:10:57] No errors found for "demo.test.ts"
[18:10:57] Marking "demo" as failed with 1 errors
[18:10:57] No errors found for "demo.test.ts"
[18:10:57] Ending test run demo.test.ts
[INFO 18:14:39] [API] Vitest process 19508 closed successfully
[INFO 18:14:39] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:14:39] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19610 created
[INFO 18:14:39] [API] Collecting tests: demo.test.ts
[18:14:39] Not starting the runner because tests are being collected
[18:14:40] There is no test run for "demo.test.ts"
[18:14:40] No test run to finish for demo.test.ts
[INFO 18:14:41] Running 1 file(s) with name pattern: ^\s?demo$
[18:14:41] The runner is starting because tests demo.test.ts were started due to a file change
[18:14:41] Enqueuing "demo"
[18:14:41] No task result for "demo", assuming the test just started running
[18:14:41] No errors found for "demo.test.ts"
[18:14:41] Marking "demo" as failed with 1 errors
[18:14:41] No errors found for "demo.test.ts"
[18:14:41] Ending test run demo.test.ts
[INFO 18:14:42] Running 1 file(s) with name pattern: ^\s?demo$
[18:14:42] The runner is starting because tests demo.test.ts were started due to a file change
[18:14:42] Enqueuing "demo"
[18:14:42] No task result for "demo", assuming the test just started running
[18:14:42] No errors found for "demo.test.ts"
[18:14:42] Marking "demo" as failed with 1 errors
[18:14:42] No errors found for "demo.test.ts"
[18:14:42] Ending test run demo.test.ts
[INFO 18:14:45] Running 1 file(s) with name pattern: ^\s?demo$
[18:14:45] The runner is starting because tests demo.test.ts were started due to a file change
[18:14:45] Enqueuing "demo"
[18:14:45] No task result for "demo", assuming the test just started running
[18:14:45] No errors found for "demo.test.ts"
[18:14:45] Marking "demo" as failed with 1 errors
[18:14:45] No errors found for "demo.test.ts"
[18:14:45] Ending test run demo.test.ts
[INFO 18:14:59] [API] Vitest process 19610 closed successfully
[INFO 18:14:59] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:14:59] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19652 created
[INFO 18:14:59] [API] Collecting tests: demo.test.ts
[18:14:59] Not starting the runner because tests are being collected
[18:14:59] There is no test run for "demo.test.ts"
[18:14:59] No test run to finish for demo.test.ts
[INFO 18:15:00] Running 1 file(s) with name pattern: ^\s?demo$
[18:15:00] The runner is starting because tests demo.test.ts were started due to a file change
[18:15:00] Enqueuing "demo"
[18:15:00] No task result for "demo", assuming the test just started running
[18:15:00] No errors found for "demo.test.ts"
[18:15:00] Marking "demo" as failed with 1 errors
[18:15:00] No errors found for "demo.test.ts"
[18:15:00] Ending test run demo.test.ts
[INFO 18:15:01] Running 1 file(s) with name pattern: ^\s?demo$
[18:15:01] The runner is starting because tests demo.test.ts were started due to a file change
[18:15:01] Enqueuing "demo"
[18:15:01] No task result for "demo", assuming the test just started running
[18:15:01] No errors found for "demo.test.ts"
[18:15:01] Marking "demo" as failed with 1 errors
[18:15:01] No errors found for "demo.test.ts"
[18:15:01] Ending test run demo.test.ts
[INFO 18:15:02] Running 1 file(s) with name pattern: ^\s?demo$
[18:15:02] The runner is starting because tests demo.test.ts were started due to a file change
[18:15:02] Enqueuing "demo"
[18:15:02] No task result for "demo", assuming the test just started running
[18:15:02] No errors found for "demo.test.ts"
[18:15:02] Marking "demo" as failed with 1 errors
[18:15:02] No errors found for "demo.test.ts"
[18:15:02] Ending test run demo.test.ts
[INFO 18:15:03] Running 1 file(s) with name pattern: ^\s?demo$
[18:15:03] The runner is starting because tests demo.test.ts were started due to a file change
[18:15:03] Enqueuing "demo"
[18:15:03] No task result for "demo", assuming the test just started running
[18:15:03] No errors found for "demo.test.ts"
[18:15:03] Marking "demo" as failed with 1 errors
[18:15:03] No errors found for "demo.test.ts"
[18:15:03] Ending test run demo.test.ts
[INFO 18:15:04] Running 1 file(s) with name pattern: ^\s?demo$
[18:15:04] The runner is starting because tests demo.test.ts were started due to a file change
[18:15:04] Enqueuing "demo"
[18:15:04] No task result for "demo", assuming the test just started running
[18:15:04] No errors found for "demo.test.ts"
[18:15:04] Marking "demo" as failed with 1 errors
[18:15:04] No errors found for "demo.test.ts"
[18:15:04] Ending test run demo.test.ts
[INFO 18:16:13] [API] Vitest process 19652 closed successfully
[INFO 18:16:13] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:16:13] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19729 created
[INFO 18:16:13] [API] Collecting tests: demo.test.ts
[18:16:13] Not starting the runner because tests are being collected
[18:16:13] There is no test run for "demo.test.ts"
[18:16:13] No test run to finish for demo.test.ts
[INFO 18:16:14] Running 1 file(s) with name pattern: ^\s?demo$
[18:16:14] The runner is starting because tests demo.test.ts were started due to a file change
[18:16:14] Enqueuing "demo"
[18:16:15] No task result for "demo", assuming the test just started running
[18:16:15] No errors found for "demo.test.ts"
[18:16:15] Marking "demo" as failed with 1 errors
[18:16:15] No errors found for "demo.test.ts"
[18:16:15] Ending test run demo.test.ts
[INFO 18:19:16] [API] Vitest process 19729 closed successfully
[INFO 18:19:16] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:19:16] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19845 created
[INFO 18:19:16] [API] Collecting tests: demo.test.ts
[18:19:16] Not starting the runner because tests are being collected
[18:19:16] There is no test run for "demo.test.ts"
[18:19:16] No test run to finish for demo.test.ts
[INFO 18:19:17] Running 1 file(s) with name pattern: ^\s?demo$
[18:19:17] The runner is starting because tests demo.test.ts were started due to a file change
[18:19:17] Enqueuing "demo"
[18:19:17] No task result for "demo", assuming the test just started running
[18:19:17] No errors found for "demo.test.ts"
[18:19:17] Marking "demo" as failed with 1 errors
[18:19:17] No errors found for "demo.test.ts"
[18:19:17] Ending test run demo.test.ts
[INFO 18:19:35] [API] Vitest process 19845 closed successfully
[INFO 18:19:35] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:19:35] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19879 created
[INFO 18:19:35] [API] Collecting tests: demo.test.ts
[18:19:35] Not starting the runner because tests are being collected
[18:19:35] There is no test run for "demo.test.ts"
[18:19:35] No test run to finish for demo.test.ts
[INFO 18:20:15] [API] Vitest process 19879 closed successfully
[INFO 18:20:15] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:20:15] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19922 created
[INFO 18:20:15] [API] Collecting tests: demo.test.ts
[18:20:15] Not starting the runner because tests are being collected
[18:20:15] There is no test run for "demo.test.ts"
[18:20:15] No test run to finish for demo.test.ts
[INFO 18:20:16] [API] Vitest process 19922 closed successfully
[INFO 18:20:16] [API] Running Vitest v2.1.1 (vitest-demo/vitest.config.ts) with Node.js@v20.15.1: /Users/dmitriy/.nvm/current/bin/node 
[INFO 18:20:16] [API] Vitest v2.1.1 (vitest-demo/vitest.config.ts) process 19942 created
[INFO 18:20:16] [API] Collecting tests: demo.test.ts
[18:20:16] Not starting the runner because tests are being collected
[18:20:17] There is no test run for "demo.test.ts"
[18:20:17] No test run to finish for demo.test.ts
[INFO 18:20:17] [API] Collecting tests: demo.test.ts
[18:20:17] Not starting the runner because tests are being collected
[18:20:17] There is no test run for "demo.test.ts"
[18:20:17] No test run to finish for demo.test.ts
[INFO 18:20:18] Running all tests in vitest-demo
[18:20:18] The runner is starting because tests demo.test.ts were started due to a file change
[18:20:18] Enqueuing "demo.test.ts"
[18:20:18] Enqueuing "demo"
[18:20:18] No task result for "demo", assuming the test just started running
[18:20:18] No errors found for "demo.test.ts"
[18:20:18] Marking "demo" as failed with 1 errors
[18:20:18] No errors found for "demo.test.ts"
[18:20:18] Ending test run demo.test.ts

Version

1.2.17

Validations

• Check that you are using the latest version of the extension
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[jimmyn]

Interestingly expect(error).toBeNull() does not show the diff view, however expect(error).toBe(null) does.

Both expect(error).toBeUndefined() and expect(error).toBe(undefined) do not show the diff