feat: verify network existence via docker CLI in integration tests

Adds dockerNetworkExists() helper and docker network inspect calls to
verify networks are actually created/destroyed at the Docker level,
not just via dokku's return values.

Author: josegonzalez

tasks/integration_test.go

@@ -204,6 +204,17 @@ func TestIntegrationAppCreateAndDestroy(t *testing.T) {
 	}
 }
 
+func dockerNetworkExists(name string) bool {
+	result, err := subprocess.CallExecCommand(subprocess.ExecCommandInput{
+		Command: "docker",
+		Args:    []string{"network", "inspect", name, "--format", "{{.Name}}"},
+	})
+	if err != nil {
+		return false
+	}
+	return strings.TrimSpace(result.StdoutContents()) == name
+}
+
 func TestIntegrationNetworkCreateAndDestroy(t *testing.T) {
 	skipIfNoDokkuT(t)
 
@@ -212,6 +223,11 @@ func TestIntegrationNetworkCreateAndDestroy(t *testing.T) {
 	// ensure clean state
 	destroyNetwork(networkName)
 
+	// verify network does not exist via docker cli
+	if dockerNetworkExists(networkName) {
+		t.Fatal("expected network to not exist before creation")
+	}
+
 	// create the network
 	task := NetworkTask{Name: networkName, State: StatePresent}
 	result := task.Execute()
@@ -225,6 +241,24 @@ func TestIntegrationNetworkCreateAndDestroy(t *testing.T) {
 		t.Error("expected changed=true for new network creation")
 	}
 
+	// verify network exists via docker cli
+	if !dockerNetworkExists(networkName) {
+		t.Fatal("expected network to exist after creation")
+	}
+
+	// verify network driver via docker cli
+	inspectResult, err := subprocess.CallExecCommand(subprocess.ExecCommandInput{
+		Command: "docker",
+		Args:    []string{"network", "inspect", networkName, "--format", "{{.Driver}}"},
+	})
+	if err != nil {
+		t.Fatalf("failed to inspect network driver: %v", err)
+	}
+	driver := strings.TrimSpace(inspectResult.StdoutContents())
+	if driver != "bridge" {
+		t.Errorf("expected network driver 'bridge', got '%s'", driver)
+	}
+
 	// creating again should be idempotent
 	result = task.Execute()
 	if result.Error != nil {
@@ -250,6 +284,11 @@ func TestIntegrationNetworkCreateAndDestroy(t *testing.T) {
 		t.Error("expected changed=true for network destruction")
 	}
 
+	// verify network does not exist via docker cli after destroy
+	if dockerNetworkExists(networkName) {
+		t.Fatal("expected network to not exist after destruction")
+	}
+
 	// destroying again should be idempotent
 	result = destroyTask.Execute()
 	if result.Error != nil {