test(agentcompat): add agent runtime harness

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/agent/prepared_binary_concurrency_test.go

@@ -0,0 +1,57 @@
+//go:build linux && agentcompat
+
+package agent
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPreparedBinary_ConcurrentConsumersSharePathAndBlockClose(t *testing.T) {
+	prepared, err := PrepareBinary(t.Context(), testAgentSourceDir(t))
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = prepared.Close() })
+
+	releases := make(chan func(), 8)
+	errorsChannel := make(chan error, 8)
+	var acquireGroup sync.WaitGroup
+	for range 8 {
+		acquireGroup.Add(1)
+		go func() {
+			defer acquireGroup.Done()
+			path, release, acquireErr := prepared.acquire()
+			if acquireErr == nil && path != prepared.BinaryPath() {
+				acquireErr = fmt.Errorf("acquired path %q differs from prepared path", path)
+			}
+			errorsChannel <- acquireErr
+			if acquireErr == nil {
+				releases <- release
+			}
+		}()
+	}
+	acquireGroup.Wait()
+	close(errorsChannel)
+	close(releases)
+	for acquireErr := range errorsChannel {
+		require.NoError(t, acquireErr)
+	}
+
+	closeErr := prepared.Close()
+	var usageErr *PreparedBinaryUsageError
+	require.ErrorAs(t, closeErr, &usageErr)
+	require.Equal(t, "has active consumers", usageErr.Reason)
+
+	var releaseGroup sync.WaitGroup
+	for release := range releases {
+		releaseGroup.Add(1)
+		go func() {
+			defer releaseGroup.Done()
+			release()
+		}()
+	}
+	releaseGroup.Wait()
+	require.NoError(t, prepared.Close())
+}