internal/covsnap/covsnap_test.go

Ref: Size: 1.9 KiB History
package covsnap

import (
	"context"
	"os"
	"syscall"
	"testing"
	"time"
)

// TestInstall_SignalTriggersWrite verifies that once Install is called with
// GOCOVERDIR set, sending SIGUSR1 to the process invokes the write seam with
// the configured directory.
func TestInstall_SignalTriggersWrite(t *testing.T) {
	dir := t.TempDir()
	t.Setenv("GOCOVERDIR", dir)

	origWrite := write
	t.Cleanup(func() { write = origWrite })

	calls := make(chan string, 1)
	write = func(d string) error {
		calls <- d
		return nil
	}

	ctx, cancel := context.WithCancel(context.Background())
	t.Cleanup(cancel)

	// Tear the handler down synchronously when the test ends: without stop the
	// SIGUSR1 handler outlives this test, and the next test's signal races this
	// test's write seam through the package-level var.
	stop := Install(ctx)
	t.Cleanup(stop)

	if err := syscall.Kill(os.Getpid(), syscall.SIGUSR1); err != nil {
		t.Fatalf("failed to send SIGUSR1: %v", err)
	}

	select {
	case got := <-calls:
		if got != dir {
			t.Fatalf("write called with dir %q, want %q", got, dir)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("timed out waiting for write to be called after SIGUSR1")
	}
}

// TestInstall_NoGOCOVERDIR verifies that Install is a no-op when GOCOVERDIR
// is unset: no handler is registered, so sending SIGUSR1 never calls write
// and never panics.
func TestInstall_NoGOCOVERDIR(t *testing.T) {
	t.Setenv("GOCOVERDIR", "")

	origWrite := write
	t.Cleanup(func() { write = origWrite })

	calls := make(chan string, 1)
	write = func(d string) error {
		calls <- d
		return nil
	}

	ctx, cancel := context.WithCancel(context.Background())
	t.Cleanup(cancel)

	stop := Install(ctx)
	t.Cleanup(stop)

	if err := syscall.Kill(os.Getpid(), syscall.SIGUSR1); err != nil {
		t.Fatalf("failed to send SIGUSR1: %v", err)
	}

	select {
	case got := <-calls:
		t.Fatalf("write unexpectedly called with dir %q", got)
	case <-time.After(200 * time.Millisecond):
		// expected: nothing fired
	}
}