Add debug logging for test execution with BUN_DEBUG_jest=1#23796
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This adds a debug log that prints the name of each test when the execution sequence starts (before beforeEach hooks run). The log is controlled by the BUN_DEBUG_jest=1 environment variable. When enabled, it prints: [jest] Running test: <test name> If a test has no name, it prints: [jest] Running test: (unnamed) This helps with debugging test execution flow and is only available in debug builds.
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WalkthroughAdds logging functionality to the Jest test runner by introducing a new log statement in Changes
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src/bun.js/test/Execution.zig(2 hunks)
🧰 Additional context used
📓 Path-based instructions (3)
**/*.zig
📄 CodeRabbit inference engine (.cursor/rules/javascriptcore-class.mdc)
**/*.zig: Declare the extern C symbol in Zig and export a Zig-friendly alias for use
Wrap the Bun____toJS extern in a Zig method that takes a JSGlobalObject and returns JSC.JSValue
Files:
src/bun.js/test/Execution.zig
src/bun.js/**/*.zig
📄 CodeRabbit inference engine (.cursor/rules/zig-javascriptcore-classes.mdc)
src/bun.js/**/*.zig: In Zig binding structs, expose generated bindings via pub const js = JSC.Codegen.JS and re-export toJS/fromJS/fromJSDirect
Constructors and prototype methods should return bun.JSError!JSC.JSValue to integrate Zig error handling with JS exceptions
Use parameter name globalObject (not ctx) and accept (*JSC.JSGlobalObject, *JSC.CallFrame) in binding methods/constructors
Implement getters as get(this, globalObject) returning JSC.JSValue and matching the .classes.ts interface
Provide deinit() for resource cleanup and finalize() that calls deinit(); use bun.destroy(this) or appropriate destroy pattern
Access JS call data via CallFrame (argument(i), argumentCount(), thisValue()) and throw errors with globalObject.throw(...)
For properties marked cache: true, use the generated Zig accessors (NameSetCached/GetCached) to work with GC-owned values
In finalize() for objects holding JS references, release them using .deref() before destroy
Files:
src/bun.js/test/Execution.zig
src/**/*.zig
📄 CodeRabbit inference engine (CLAUDE.md)
In Zig code, manage memory carefully and use defer for cleanup of allocations/resources
When adding debug logs in Zig, create a scoped logger and log via Bun APIs:
const log = bun.Output.scoped(.${SCOPE}, .hidden);thenlog("...", .{})
src/**/*.zig: Use private fields in Zig with the#prefix (e.g.,struct { #foo: u32 };)
Prefer decl literals in Zig (e.g.,const decl: Decl = .{ .binding = 0, .value = 0 };)
Prefer placing@importstatements at the bottom of the Zig file (formatter may reorder automatically)
Prefer@import("bun")rather than@import("root").bunor@import("../bun.zig")
Files:
src/bun.js/test/Execution.zig
🧠 Learnings (1)
📚 Learning: 2025-10-08T03:11:45.286Z
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/building-bun.mdc:0-0
Timestamp: 2025-10-08T03:11:45.286Z
Learning: Applies to src/**/*.zig : When adding debug logs in Zig, create a scoped logger and log via Bun APIs: `const log = bun.Output.scoped(.${SCOPE}, .hidden);` then `log("...", .{})`
Applied to files:
src/bun.js/test/Execution.zig
🔇 Additional comments (1)
src/bun.js/test/Execution.zig (1)
497-498: Log implementation looks good, pending visibility fix.The log call correctly:
- Uses
std.zig.fmtEscapesto escape the test name- Handles unnamed tests with a fallback
- Is guarded by appropriate conditions (test_entry exists and has a callback)
- Provides a clear, descriptive message
Note: The effectiveness of this logging depends on the visibility level being correctly set to
.hiddenin thelogconstant declaration (see previous comment).
| const log = bun.Output.scoped(.jest, .visible); | ||
|
|
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🧩 Analysis chain
Verify the visibility level: should this be .hidden instead of .visible?
According to the coding guideline and the PR description, debug logs should use .hidden to gate them behind the BUN_DEBUG_jest=1 environment variable. The current implementation uses .visible, which may cause these logs to always appear rather than only when the environment variable is set.
Based on learnings
Apply this diff if .hidden is the correct visibility level:
-const log = bun.Output.scoped(.jest, .visible);
+const log = bun.Output.scoped(.jest, .hidden);Alternatively, please confirm whether .visible is intentional and explain how the BUN_DEBUG_jest=1 environment variable gates the output with this visibility setting.
I need to investigate the codebase to verify the correct visibility level for the logger.
---
🏁 Script executed:
```shell
#!/bin/bash
# Find examples of bun.Output.scoped usage in Zig files to identify the correct pattern
rg -n 'bun\.Output\.scoped' --type zig -B2 -A2
Length of output: 39967
🏁 Script executed:
#!/bin/bash
# Search for BUN_DEBUG environment variable usage to understand gating behavior
rg -n 'BUN_DEBUG' --type zig -B3 -A3 | head -100Length of output: 6820
🏁 Script executed:
#!/bin/bash
# Check if there's documentation or configuration for visibility levels
rg -n '\.hidden|\.visible' --type zig | grep -i output | head -50Length of output: 4349
🏁 Script executed:
#!/bin/bash
# Look at the context around line 624 in the file under review to confirm the scope
sed -n '620,630p' src/bun.js/test/Execution.zigLength of output: 207
🏁 Script executed:
#!/bin/bash
# Search for other loggers declared in Execution.zig or nearby test files
rg -n 'const log = ' src/bun.js/test/ --type zig -B1 -A1Length of output: 151
Change .visible to .hidden to enable environment variable gating.
The logger at line 624 currently uses .visible, which makes logs always appear. However, the PR states logging should be "enabled by the environment variable BUN_DEBUG_jest=1". According to src/output.zig (lines 767-773), this behavior requires .hidden visibility. Additionally, src/cli/test/Scanner.zig:18 already declares a jest-scoped logger with .hidden, confirming the correct pattern for this module.
-const log = bun.Output.scoped(.jest, .visible);
+const log = bun.Output.scoped(.jest, .hidden);📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| const log = bun.Output.scoped(.jest, .visible); | |
| const log = bun.Output.scoped(.jest, .hidden); |
🤖 Prompt for AI Agents
In src/bun.js/test/Execution.zig around lines 624-625, the logger is created
with bun.Output.scoped(.jest, .visible) which forces logs to always appear;
change the visibility argument from .visible to .hidden so the jest-scoped
logger respects the environment gating (BUN_DEBUG_jest=1) as implemented in
src/output.zig and consistent with src/cli/test/Scanner.zig: use
bun.Output.scoped(.jest, .hidden) instead.
There was a problem hiding this comment.
Visible means it is enabled by default in debug builds unless BUN_DEBUG_QUIET_LOGS=1 is set, which is what we want. If that is set, then it is only enabled with BUN_DEBUG_jest=1
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@pfgithub Thank you for the clarification! I understand now—.visible is indeed the correct choice here. It enables the logs by default in debug builds, while still respecting BUN_DEBUG_QUIET_LOGS=1 to silence them, and BUN_DEBUG_jest=1 to re-enable them when quieted.
I appreciate you taking the time to explain the distinction between .visible and .hidden for scoped loggers. This is helpful context for understanding the debug logging system.
/)_/)
(o.o) oops, my mistake!
( )
✏️ Learnings added
Learnt from: pfgithub
PR: oven-sh/bun#23796
File: src/bun.js/test/Execution.zig:624-625
Timestamp: 2025-10-18T02:06:31.595Z
Learning: In Zig files using bun.Output.scoped(), the visibility level `.visible` means logs are enabled by default in debug builds unless `BUN_DEBUG_QUIET_LOGS=1` is set; if that environment variable is set, the logs can be re-enabled with `BUN_DEBUG_<scope>=1`. Use `.visible` for logs that should appear by default in debug builds, and `.hidden` for logs that require explicit opt-in via `BUN_DEBUG_<scope>=1`.
Note: Learnings are effective only in the context of similar code segments. To apply general coding guidelines, please configure review instructions. You can manage existing learnings in the app.
🧠 Learnings used
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-08-30T00:13:36.815Z
Learning: Applies to src/bun.js/**/*.zig : Constructors and prototype methods should return bun.JSError!JSC.JSValue to integrate Zig error handling with JS exceptions
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/building-bun.mdc:0-0
Timestamp: 2025-10-08T03:11:45.286Z
Learning: Applies to src/**/*.zig : When adding debug logs in Zig, create a scoped logger and log via Bun APIs: `const log = bun.Output.scoped(.${SCOPE}, .hidden);` then `log("...", .{})`
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-08-30T00:11:57.076Z
Learning: Applies to src/{**/js_*.zig,bun.js/api/**/*.zig} : Use bun.JSError!JSValue for proper error propagation in JS-exposed Zig functions
Learnt from: CR
PR: oven-sh/bun#0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-08-30T00:13:36.815Z
Learning: Applies to src/bun.js/**/*.zig : Access JS call data via CallFrame (argument(i), argumentCount(), thisValue()) and throw errors with globalObject.throw(...)
Learnt from: CR
PR: oven-sh/bun#0
File: CLAUDE.md:0-0
Timestamp: 2025-10-04T09:51:30.294Z
Learning: Use BUN_DEBUG_QUIET_LOGS=1 to silence debug logs or BUN_DEBUG_<scope>=1 to enable scoped logs in debug builds
3 participants
Summary
Adds debug logging that prints the name of each test when it starts running, controlled by the
BUN_DEBUG_jest=1environment variable.Changes
src/bun.js/test/Execution.zigto add logging in theonEntryStarted()functionbun.Output.scoped(.jest, .visible)BUN_DEBUG_jest=1is set, prints:[jest] Running test: <test name>Testing
Manually tested with various test files:
Without BUN_DEBUG_jest:
With BUN_DEBUG_jest=1:
Also tested with nested describe blocks and all test names are logged correctly.
Notes