How to debug Zig tests in VSCode

zig_test_debugging_vscode.md

Tested on macOS:

1. Install the CodeLLDB VSCode extension. Unlike the debugger in the C/C++ extension, this allows to set breakpoints inside Zig "test" blocks (in the MS C/C++ extension debugger, breakpoints inside test blocks will be disabled once the debugger starts for unknown reasons.
2. When compiling the test, tell it to also emit a binary: zig test -femit-bin=zig-out/bin/my-test src/bla.zig, otherwise there will be no executable to debug.
3. The compiled test executable expects the path to the Zig executable as first command line argument, the launch.json file needs to be setup accordingly (note the args item):

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "lldb",
            "request": "launch",
            "name": "Debug",
            "program": "${workspaceFolder}/zig-out/bin/my-test",
            "args": ["/usr/local/bin/zig"],
            "cwd": "${workspaceFolder}",
            
        }
    ]
}

That should be all, now set breakpoints inside tests and start the debugger with F5.

Works without args in launch.json

Thanks, I was needing this. I included some additional things to run only the tests of a file in case anybody need this later.

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "lldb",
            "request": "launch",
            "name": "Debug test",
            "program": "${workspaceFolder}/zig-out/bin/${fileBasenameNoExtension}test",
            "args": [],
            "cwd": "${workspaceFolder}",
            "preLaunchTask": "build zig test"
        }
    ]
}

tasks.json

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "build zig test",
            "type": "shell",
            "command": "zig test -femit-bin=zig-out/bin/${fileBasenameNoExtension}test ${relativeFile}"
        }
    ]
}

I found that the above solution runs tests twice. I was able to fix this with some slight modifications:

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "lldb",
            "request": "launch",
            "name": "Debug test",
            "program": "${workspaceFolder}/zig-out/bin/${fileBasenameNoExtension}-test",
            "args": [],
            "cwd": "${workspaceFolder}",
            "preLaunchTask": "test",
        }
    ]
}

tasks.json

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "test",
            "type": "shell",
            "command": "zig",
            "args": [
                "test",
                "-femit-bin=zig-out/bin/${fileBasenameNoExtension}-test",
                "--test-no-exec",
                "${relativeFile}",
            ]
        }
    ]
}

Notice the additional argument --test-no-exec. This will cause the test runner to emit the binary test file without actually running the tests.

I have this exact setup but breakpoints are not breaking

My current setup is a combination of the VSCode Zig extension (https://marketplace.visualstudio.com/items?itemName=ziglang.vscode-zig) and CodeLLDB with the following vanilla launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "lldb",
            "request": "launch",
            "name": "Debug",
            "program": "${workspaceFolder}/zig-out/bin/kc853",
            "args": [],
            "cwd": "${workspaceFolder}"
        }
    ]
}

Debugging and breakpoints work (on macOS). Only bug I see is a debug line mismatch at the end of scope blocks. Sometimes the debugger appears to step through or stop at the last line of an if-else else branch even though that else branch isn't taken.

For tests I simply install them as artifact, so that an executable file is created in the file system, and simply build them during zig build:

https://github.com/floooh/chipz/blob/8dd374eb1e5605e1f86f0d3cd7206e8ddf1f29a5/tests/build.zig#L37-L56

@DayBr3ak maybe it's because you are on windows. Replace lldb with cppvsdbg

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "cppvsdbg",
            "request": "launch",
            "name": "Debug test",
            "program": "${workspaceFolder}/zig-out/bin/${fileBasenameNoExtension}-test",
            "args": [],
            "cwd": "${workspaceFolder}",
            "preLaunchTask": "test",
        }
    ]
}