Use fputs for stderr writes in Logger - #416

What was wrong

3.0 moved Logger.error and Logger.warning to stderr via FileHandle.standardError.write. That introduced two problems:

1. Output ordering. print writes to a block-buffered stdout when output is piped; FileHandle.write is unbuffered. Under 2>&1 (i.e. any CI log), warnings/errors jumped ahead of the "Report successfully created" line instead of interleaving where they actually occurred.
2. Crash on a closed descriptor. FileHandle.write raises an uncatchable Objective-C exception, so xchtmlreport … 2>&- crashed where it previously failed silently.

Fixes #390.

What changed

Only Sources/XCTestHTMLReportCore/Classes/Helpers/Logger.swift: printToStandardError now flushes stdout and uses fputs(message + "\n", stderr) instead of FileHandle.standardError.write. error and warning still go to stderr; success, step, and substep are untouched and remain on stdout (verified by the CLI test suite, which parses Logger.success output from stdout).

     private static func printToStandardError(_ message: String) {
-        FileHandle.standardError.write(Data((message + "\n").utf8))
+        // `FileHandle.write` is unbuffered while `print`'s stdout is block-buffered
+        // when piped, so under `2>&1` these lines would jump ahead of stdout output
+        // instead of interleaving where they occurred. It also raises an uncatchable
+        // Objective-C exception when the descriptor is closed (e.g. `2>&-`). `fputs`
+        // avoids both problems. Flushing stdout first keeps interleaving accurate.
+        fflush(stdout)
+        fputs(message + "\n", stderr)
     }

Verification

All commands run from a clean checkout of this branch, fixtures generated via ./prepareTestResults.sh.

1. swift build — clean

Build complete! (1.23s)

2. swift test — 22 tests, 1 skipped, 0 failures

Test Suite 'XCTestHTMLReportPackageTests.xctest' passed at 2026-08-07 18:01:18.640.
	 Executed 22 tests, with 1 test skipped and 0 failures (0 unexpected) in 12.363 (12.367) seconds
Test Suite 'All tests' passed at 2026-08-07 18:01:18.640.
	 Executed 22 tests, with 1 test skipped and 0 failures (0 unexpected) in 12.363 (12.368) seconds

(CoreTests.testRetryFunctionalityJunit is skipped pending #378, as expected.)

3. Ordering fix, using a degraded bundle (mkdir -p /tmp/Broken.xcresult) piped with > out.log 2>&1:

Before this fix (stashed the change, rebuilt), the success line was pushed to the very end, after all the warnings that were chronologically emitted later:

1	Error: Failed to create a new result bundle reader, underlying error: Info.plist at /tmp/Broken.xcresult/Info.plist does not exist, the result bundle might be corrupted or the provided path is not a result bundle
2	Warning: Can't find invocation record for : /tmp/Broken.xcresult
3	Warning: Report is degraded: 1 fault(s)
4	Warning:   missingInvocationRecord: /tmp/Broken.xcresult
5	Error: Exiting non-zero. Pass --lenient to ignore faults.
6	
7	Report successfully created at /tmp/broken-out/index.html

After this fix, "Report successfully created" appears in its correct chronological position — before the later degradation warnings that are emitted after the report is written:

1	Error: Failed to create a new result bundle reader, underlying error: Info.plist at /tmp/Broken.xcresult/Info.plist does not exist, the result bundle might be corrupted or the provided path is not a result bundle
2	Warning: Can't find invocation record for : /tmp/Broken.xcresult
3	
4	Report successfully created at /tmp/broken-out/index.html
5	Warning: Report is degraded: 1 fault(s)
6	Warning:   missingInvocationRecord: /tmp/Broken.xcresult
7	Error: Exiting non-zero. Pass --lenient to ignore faults.

4. Crash fix, running with stderr closed (xchtmlreport -o /tmp/broken-out /tmp/Broken.xcresult 2>&-):

Before this fix:

line 3: 76010 Abort trap: 6           "$BIN" -o /tmp/broken-out /tmp/Broken.xcresult 2>&-
EXIT CODE: 134

After this fix:

Report successfully created at /tmp/broken-out/index.html
EXIT CODE: 3

No crash; exits cleanly with code 3 (faults were collected, as expected for a broken bundle).

5. Logger.success still on stdout (xchtmlreport -o /tmp/broken-out /tmp/Broken.xcresult 2>/dev/null):

Report successfully created at /tmp/broken-out/index.html

Concerns

None. The change is scoped to the single private helper method in Logger.swift.

🤖 Generated with Claude Code