fix(auth): harden diagnostic cleanup races

tools/tht/internal/compose/process_termination_test.go

@@ -0,0 +1,89 @@
+package compose
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestWindowsCancellationTreatsProcessReapedBeforeTreeTerminationAsSuccess(t *testing.T) {
+	done := make(chan error, 1)
+	done <- nil
+	treeCalls := 0
+	directCalls := 0
+
+	err := terminateWindowsProcess(done, func() error {
+		treeCalls++
+		return errors.New("tree termination should not run")
+	}, func() error {
+		directCalls++
+		return errors.New("direct termination should not run")
+	}, 0)
+
+	if err != nil {
+		t.Fatalf("terminateWindowsProcess() error = %v, want nil", err)
+	}
+	if treeCalls != 0 || directCalls != 0 {
+		t.Fatalf("termination calls = tree:%d direct:%d, want none", treeCalls, directCalls)
+	}
+}
+
+func TestWindowsCancellationTreatsProcessReapedAfterTreeTerminationAsSuccess(t *testing.T) {
+	done := make(chan error, 1)
+	directCalls := 0
+
+	err := terminateWindowsProcess(done, func() error {
+		done <- nil
+		return ErrProcessReap
+	}, func() error {
+		directCalls++
+		return errors.New("direct termination should not run")
+	}, 0)
+
+	if err != nil {
+		t.Fatalf("terminateWindowsProcess() error = %v, want nil", err)
+	}
+	if directCalls != 0 {
+		t.Fatalf("direct termination calls = %d, want 0", directCalls)
+	}
+}
+
+func TestWindowsCancellationTreatsProcessReapedAfterDirectTerminationAsSuccess(t *testing.T) {
+	done := make(chan error, 1)
+	directCalls := 0
+
+	err := terminateWindowsProcess(done, func() error {
+		return ErrProcessReap
+	}, func() error {
+		directCalls++
+		done <- nil
+		return ErrProcessReap
+	}, 0)
+
+	if err != nil {
+		t.Fatalf("terminateWindowsProcess() error = %v, want nil", err)
+	}
+	if directCalls != 1 {
+		t.Fatalf("direct termination calls = %d, want 1", directCalls)
+	}
+}
+
+func TestWindowsCancellationReportsReapFailureWhenProcessSurvives(t *testing.T) {
+	done := make(chan error)
+	treeCalls := 0
+	directCalls := 0
+
+	err := terminateWindowsProcess(done, func() error {
+		treeCalls++
+		return ErrProcessReap
+	}, func() error {
+		directCalls++
+		return ErrProcessReap
+	}, 0)
+
+	if !errors.Is(err, ErrProcessReap) {
+		t.Fatalf("terminateWindowsProcess() error = %v, want ErrProcessReap", err)
+	}
+	if treeCalls != 1 || directCalls != 1 {
+		t.Fatalf("termination calls = tree:%d direct:%d, want one each", treeCalls, directCalls)
+	}
+}