V8 coverage provider does not properly report react coverage, istanbul does #7660
Description
Describe the bug
I have a project (in deno) that works using my own library; thankfully i got testing working after a lot of back and forth.
I am now trying to get coverage to work properly. After failing all day i tried to use istanbul instead of v8 just for the hell of it and for some reason that works?
The bug: Using V8 instead of istanbul as a provider for coverage makes all lines "miss". The output between the two are inconsistent.
The project i mean can be found here: https://gitlab.zweieuro.at/wui/projects/vivaci-ui-deno (branch "vitest-bug")
Command: deno task test:coverage
How to reproduce: Using v8 as a provider will print:
Task test:coverage deno -A --node-modules-dir=auto npm:vitest run --coverage -c ./vite.config.ts
RUN v3.0.8 /home/zweieuro/Documents/uni/2023_SS/WUI/html_UI/vivaci_ui_deno/client
Coverage enabled with v8
✓ tests/ScoreDisplay.test.tsx (3 tests) 33ms
✓ tests/App.test.tsx (2 tests) 30ms
Test Files 2 passed (2)
Tests 5 passed (5)
Start at 16:55:22
Duration 4.18s (transform 3.54s, setup 5.23s, collect 1.54s, tests 63ms, environment 471ms, prepare 76ms)
% Coverage report from v8
--------------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
--------------------|---------|----------|---------|---------|-------------------
All files | 0 | 20 | 20 | 0 |
App.tsx | 0 | 0 | 0 | 0 | 1-57
HighscoreInput.tsx | 0 | 0 | 0 | 0 | 1-64
LifeIcon.tsx | 0 | 100 | 100 | 0 | 2-15
ScoreDisplay.tsx | 0 | 0 | 0 | 0 | 1-71
main.tsx | 0 | 0 | 0 | 0 | 1-11
--------------------|---------|----------|---------|---------|-------------------
Using istanbul instead:
Task test:coverage deno -A --node-modules-dir=auto npm:vitest run --coverage -c ./vite.config.ts
RUN v3.0.8 /home/zweieuro/Documents/uni/2023_SS/WUI/html_UI/vivaci_ui_deno/client
Coverage enabled with istanbul
✓ tests/ScoreDisplay.test.tsx (3 tests) 30ms
✓ tests/App.test.tsx (2 tests) 24ms
Test Files 2 passed (2)
Tests 5 passed (5)
Start at 16:55:58
Duration 4.18s (transform 3.61s, setup 5.26s, collect 1.68s, tests 54ms, environment 473ms, prepare 76ms)
% Coverage report from istanbul
--------------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
--------------------|---------|----------|---------|---------|-------------------
All files | 77.14 | 62.5 | 78.57 | 77.14 |
App.tsx | 100 | 100 | 100 | 100 |
HighscoreInput.tsx | 44.44 | 40 | 25 | 44.44 | 6,47-58
LifeIcon.tsx | 100 | 100 | 100 | 100 |
ScoreDisplay.tsx | 89.47 | 66.66 | 100 | 89.47 | 8,28
main.tsx | 0 | 100 | 100 | 0 | 7
--------------------|---------|----------|---------|---------|-------------------
I do not have full coverage, but this output makes sense.
I made a discussion which eventually lead to this but started somewhere very different: #7617
Note: The server is my private one, it may be a bit slow at times
BIG NOTE: I am using deno! which uses npm behind the scenes but i can only select package manager npm here!
Reproduction
! I am assuming you got deno installed
git clone https://gitlab.zweieuro.at/wui/projects/vivaci-ui-deno.git
cd vivaci-ui-deno
git checkout vitest-bug
deno task test:coverage
# Now change the reporter to v8
deno task test:coverage
you will end up with different output
System Info
System:
OS: Linux 6.12 Arch Linux
CPU: (16) x64 AMD Ryzen 7 7840U w/ Radeon 780M Graphics
Memory: 15.68 GB / 30.54 GB
Container: Yes
Shell: 5.2.37 - /usr/bin/bash
Binaries:
Node: 22.14.0 - ~/.nvm/versions/node/v22.14.0/bin/node
npm: 10.9.2 - ~/.nvm/versions/node/v22.14.0/bin/npmUsed Package Manager
npm
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