fix: support parallel execution of reusable containers (#593)

* chore: add a test demonstrating the bug

* fix: protect reusable containers with a mutex

* fix: typo

generic.go

@@ -4,9 +4,11 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"sync"
 )
 
 var (
+	reuseContainerMx  sync.Mutex
 	ErrReuseEmptyName = errors.New("with reuse option a container name mustn't be empty")
 )
 
@@ -56,6 +58,11 @@ func GenericContainer(ctx context.Context, req GenericContainerRequest) (Contain
 
 	var c Container
 	if req.Reuse {
+		// we must protect the reusability of the container in the case it's invoked
+		// in a parallel execution, via ParallelContainers or t.Parallel()
+		reuseContainerMx.Lock()
+		defer reuseContainerMx.Unlock()
+
 		c, err = provider.ReuseOrCreateContainer(ctx, req.ContainerRequest)
 	} else {
 		c, err = provider.CreateContainer(ctx, req.ContainerRequest)

parallel_test.go

@@ -2,9 +2,12 @@ package testcontainers
 
 import (
 	"context"
+	"fmt"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
+	"github.com/testcontainers/testcontainers-go/wait"
 )
 
 func TestParallelContainers(t *testing.T) {
@@ -120,3 +123,50 @@ func TestParallelContainers(t *testing.T) {
 		})
 	}
 }
+
+func TestParallelContainersWithReuse(t *testing.T) {
+	const (
+		postgresPort     = 5432
+		postgresPassword = "test"
+		postgresUser     = "test"
+		postgresDb       = "test"
+	)
+
+	natPort := fmt.Sprintf("%d/tcp", postgresPort)
+
+	req := GenericContainerRequest{
+		ContainerRequest: ContainerRequest{
+			Image:        "postgis/postgis",
+			Name:         "test-postgres",
+			ExposedPorts: []string{natPort},
+			Env: map[string]string{
+				"POSTGRES_PASSWORD": postgresPassword,
+				"POSTGRES_USER":     postgresUser,
+				"POSTGRES_DATABASE": postgresDb,
+			},
+			WaitingFor: wait.ForLog("database system is ready to accept connections").
+				WithPollInterval(100 * time.Millisecond).
+				WithOccurrence(2),
+		},
+		Started: true,
+		Reuse:   true,
+	}
+
+	parallelRequest := ParallelContainerRequest{
+		req,
+		req,
+		req,
+	}
+
+	ctx := context.Background()
+
+	res, err := ParallelContainers(ctx, parallelRequest, ParallelContainersOptions{})
+	if err != nil {
+		e, _ := err.(ParallelContainersError)
+		t.Fatalf("expected errors: %d, got: %d\n", 0, len(e.Errors))
+	}
+
+	for _, c := range res {
+		defer c.Terminate(ctx)
+	}
+}