Description

The app.Test() method returns "test: got empty response" errors when timeouts occur, breaking tests that worked in v2. Root cause: connection closes on timeout before ServeConn finishes writing the response, leaving the read buffer empty.

Changes introduced

Core Fix (app.go)
Modified timeout handling in Test():

• FailOnTimeout: true → closes connection, returns timeout error (unchanged)
• FailOnTimeout: false → waits up to 1 additional second for handler to complete, preventing indefinite blocking while allowing handlers to finish

// Before: connection closed regardless of FailOnTimeout value
case <-time.After(cfg.Timeout):
    conn.Close()
    if cfg.FailOnTimeout {
        return nil, os.ErrDeadlineExceeded
    }

// After: connection only closed when failing on timeout
case <-time.After(cfg.Timeout):
    if cfg.FailOnTimeout {
        conn.Close()
        return nil, os.ErrDeadlineExceeded
    }
    // Wait up to 1 additional second for handler to complete
    select {
    case err = <-channel:
    case <-time.After(time.Second):
        conn.Close()
    }

Test Updates

• Updated tests expecting interrupted behavior to explicitly set FailOnTimeout: true

• Added regression tests verifying both timeout modes work correctly with explicit delays to ensure reliable timeout triggering

• Fixed test that incorrectly expected empty response with FailOnTimeout: false

• Reduced sleep/timeout values in tests from 1s/100ms to 50ms/10ms for faster test suite execution

• Updated timeout test assertion to use ErrorIs for specific error validation

• Benchmarks: No performance impact - same code paths, adds maximum 1 second wait when FailOnTimeout is false

• Documentation Update: N/A - behavior now matches documented intent while preventing indefinite blocking

• Changelog/What's New: Fixes Test method empty response error on timeout with bounded wait time

• Migration Guide: No migration needed - fixes buggy behavior, breaking change only for tests relying on the bug

• API Alignment with Express: N/A

• API Longevity: Clarifies existing API semantics without changing signature, maintains timeout as safety limit

• Examples: Test cases demonstrate both timeout modes with proper assertions

Type of change

• Code consistency (non-breaking change which improves code reliability and robustness)

Checklist

• Followed the inspiration of the Express.js framework for new functionalities, making them similar in usage.
• Conducted a self-review of the code and provided comments for complex or critical parts.
• Updated the documentation in the /docs/ directory for Fiber's documentation.
• Added or updated unit tests to validate the effectiveness of the changes or new features.
• Ensured that new and existing unit tests pass locally with the changes.
• Verified that any new dependencies are essential and have been agreed upon by the maintainers/community.
• Aimed for optimal performance with minimal allocations in the new code.
• Provided benchmarks for the new code to analyze and improve upon.

• Fixes 🐛 [Bug]: Fiber returns err: test: got empty #4053

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