Test Improvements: internal/sys/container_test.go + container_detect_test.go

File Analyzed

• Test Files: internal/sys/container_test.go, internal/sys/container_detect_test.go
• Package: internal/sys

Improvements Made

1. Scanner-overflow coverage (new test case)

Added a test case "single line exceeding scanner buffer limit returns empty string" to TestExtractContainerIDFromContent. This covers the previously-untested scanner.Err() != nil branch in extractContainerIDFromContent (triggered when a single line exceeds bufio.MaxScanTokenSize = 65,536 bytes):

{
    name:  "single line exceeding scanner buffer limit returns empty string",
    input: strings.Repeat("x", bufio.MaxScanTokenSize+1),
    want:  "",
},

2. Parallel test execution

Added t.Parallel() to all pure-function tests (safe to run concurrently — no environment mutation, no shared state):

• TestExtractContainerIDFromContent + all 16 subtests
• TestContainsAny_Helper + all subtests
• 6 × TestExtractContainerIDFromCgroupFiles_* tests in container_detect_test.go (temp-file only, no t.Setenv)

3. Increased Coverage

• Previous coverage: extractContainerIDFromContent → 92.3%, package total → 98.9%
• New coverage: extractContainerIDFromContent → 100.0%, package total → 100.0%
• Improvement: +1.1% package, +7.7% on the targeted function

Test Execution

ok  github.com/github/gh-aw-mcpg/internal/sys  coverage: 100.0% of statements

All tests pass with -race flag enabled. Tests run multiple times with consistent results.

Why These Changes?

extractContainerIDFromContent used bufio.Scanner to parse cgroup content but the error path (scanner.Err() != nil) was never exercised — it requires a line longer than 64 KiB, an unusual but valid edge case. Adding the overflow test ensures the error path is verified. The parallelism additions are low-risk improvements to pure-function tests, reducing wall-clock test time with no behavior changes.

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