Protect blitzcc target-flag workflow coverage

test.bat

@@ -1,12 +1,17 @@
 @echo off
-setlocal
+setlocal EnableDelayedExpansion
 
 set ROOTDIR=%CD%
 
-cd %ROOTDIR%\tests
-
 set BLITZPATH=%ROOTDIR%
 set FAILED=0
+set SAMPLE=%ROOTDIR%\tests\NumberTest.bb
+
+call :expect_success "host alias compiles NumberTest" -c +q -target host "%SAMPLE%"
+call :expect_success "native Windows target compiles NumberTest" -c +q -target windows-x86 "%SAMPLE%"
+call :expect_failure "foreign macOS target is rejected" "Unsupported -target" -c +q -target macos-arm64 "%SAMPLE%"
+
+cd %ROOTDIR%\tests
 
 for /R %%f in (*.bb) do (
     "%BLITZPATH%\bin\blitzcc.exe" -t "%%f" || (echo "%%f failed at least one test" && SET FAILED=1)
@@ -15,12 +20,45 @@ for /R %%f in (*.bb) do (
 
 cd %ROOTDIR%
 
-if %FAILED% == 1 (
+if !FAILED! == 1 (
     echo "Tests failed"
     endlocal
     exit /b 1
 )
 
 echo "Tests passed"
 
-endlocal
+endlocal
+exit /b 0
+
+:expect_success
+set "LABEL=%~1"
+shift /1
+"%BLITZPATH%\bin\blitzcc.exe" %1 %2 %3 %4 %5 %6 %7 %8 %9 >nul 2>&1
+if errorlevel 1 (
+    echo target contract FAILED: !LABEL!
+    set FAILED=1
+)
+exit /b 0
+
+:expect_failure
+set "LABEL=%~1"
+set "EXPECTED=%~2"
+shift /1
+shift /1
+set "TARGET_LOG=%TEMP%\blitzforge-target-%RANDOM%-%RANDOM%.log"
+"%BLITZPATH%\bin\blitzcc.exe" %1 %2 %3 %4 %5 %6 %7 %8 %9 >"!TARGET_LOG!" 2>&1
+set "TARGET_RC=!ERRORLEVEL!"
+if !TARGET_RC! EQU 0 (
+    echo target contract FAILED: !LABEL! unexpectedly succeeded
+    set FAILED=1
+) else (
+    findstr /C:"!EXPECTED!" "!TARGET_LOG!" >nul
+    if errorlevel 1 (
+        echo target contract FAILED: !LABEL! did not report the unsupported-target error
+        type "!TARGET_LOG!"
+        set FAILED=1
+    )
+)
+del /q "!TARGET_LOG!" >nul 2>&1
+exit /b 0

test.sh

@@ -3,6 +3,8 @@ set -euo pipefail
 
 ROOTDIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 TESTDIR="${ROOTDIR}/tests"
+TEST_TMPDIR="$(mktemp -d "${TMPDIR:-/tmp}/blitzforge-tests.XXXXXX")"
+trap 'rm -rf "${TEST_TMPDIR}"' EXIT
 
 BLITZCC_UNIX="${ROOTDIR}/bin/blitzcc"
 BLITZCC_WIN="${ROOTDIR}/bin/blitzcc.exe"
@@ -24,6 +26,52 @@ else
 fi
 
 FAILED=0
+TARGET_SAMPLE="${TESTDIR}/NumberTest.bb"
+
+run_target_expect_success() {
+  local label="$1"
+  shift
+  if ! "${BLITZCC}" -c +q "$@" "${TARGET_SAMPLE}" \
+    > "${TEST_TMPDIR}/target-success.out" 2> "${TEST_TMPDIR}/target-success.err"; then
+    echo "target contract FAILED: ${label}" >&2
+    cat "${TEST_TMPDIR}/target-success.err" >&2
+    FAILED=1
+  fi
+}
+
+run_target_expect_failure() {
+  local label="$1"
+  shift
+  set +e
+  "${BLITZCC}" -c +q "$@" "${TARGET_SAMPLE}" \
+    > "${TEST_TMPDIR}/target-failure.out" 2> "${TEST_TMPDIR}/target-failure.err"
+  local rc=$?
+  set -e
+
+  if [[ "${rc}" -eq 0 ]]; then
+    echo "target contract FAILED: ${label} unexpectedly succeeded" >&2
+    FAILED=1
+    return
+  fi
+
+  if ! grep -q "Unsupported -target" "${TEST_TMPDIR}/target-failure.out"; then
+    echo "target contract FAILED: ${label} did not report the unsupported-target error" >&2
+    echo "--- stdout ---" >&2
+    cat "${TEST_TMPDIR}/target-failure.out" >&2
+    echo "--- stderr ---" >&2
+    cat "${TEST_TMPDIR}/target-failure.err" >&2
+    FAILED=1
+  fi
+}
+
+run_target_expect_success "host alias compiles NumberTest" -target host
+if [[ "$(uname -s)" == "Darwin" ]]; then
+  run_target_expect_success "native macOS target compiles NumberTest" -target macos-arm64
+  run_target_expect_failure "foreign Windows target is rejected" -target windows-x86
+else
+  run_target_expect_failure "foreign macOS target is rejected" -target macos-arm64
+fi
+
 while IFS= read -r -d '' f; do
   if ! "${BLITZCC}" "${TARGET_FLAG[@]}" "${EXEC_FLAG[@]}" -t "${f}"; then
     echo "\"${f}\" failed at least one test"
@@ -39,19 +87,17 @@ if [[ "$(uname -s)" == "Darwin" ]]; then
   # the stub runtime is still in place. It does NOT silently succeed when
   # nothing actually ran.
   STUB_SENTINEL="BlitzForge stub runtime: native execution is not yet implemented"
-  tmpdir="$(mktemp -d "${TMPDIR:-/tmp}/blitzcc-arm64-exec.XXXXXX")"
-  trap 'rm -rf "${tmpdir}"' EXIT
-  cat > "${tmpdir}/arm64_exec_smoke.bb" <<'EOF'
+  cat > "${TEST_TMPDIR}/arm64_exec_smoke.bb" <<'EOF'
 Print "arm64_exec_smoke"
 End
 EOF
   set +e
-  "${BLITZCC}" +q -target macos-arm64 "${tmpdir}/arm64_exec_smoke.bb" \
-    > "${tmpdir}/arm64_exec_smoke.out" 2> "${tmpdir}/arm64_exec_smoke.err"
+  "${BLITZCC}" +q -target macos-arm64 "${TEST_TMPDIR}/arm64_exec_smoke.bb" \
+    > "${TEST_TMPDIR}/arm64_exec_smoke.out" 2> "${TEST_TMPDIR}/arm64_exec_smoke.err"
   smoke_rc=$?
   set -e
-  smoke_stdout="$(tr -d '\r' < "${tmpdir}/arm64_exec_smoke.out")"
-  smoke_stderr="$(cat "${tmpdir}/arm64_exec_smoke.err")"
+  smoke_stdout="$(tr -d '\r' < "${TEST_TMPDIR}/arm64_exec_smoke.out")"
+  smoke_stderr="$(cat "${TEST_TMPDIR}/arm64_exec_smoke.err")"
   if [[ "${smoke_stdout}" == "arm64_exec_smoke" && "${smoke_rc}" -eq 0 ]]; then
     echo "arm64 execution smoke: native runtime executed program correctly."
   elif grep -q "${STUB_SENTINEL}" <<<"${smoke_stderr}"; then