Add network-ping CLI command to test container connectivity (#14)

* Initial plan

* Add network-ping CLI command feature

Co-authored-by: j143 <53068787+j143@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: j143 <53068787+j143@users.noreply.github.com>

Author: Copilot

main.go

@@ -272,6 +272,15 @@ func main() {
 			fmt.Printf("Error: %s\n", err)
 			return
 		}
+	case "network-ping":
+		if len(os.Args) < 5 {
+			fmt.Println("Usage: basic-docker network-ping <network-id> <source-container-id> <target-container-id>")
+			return
+		}
+		err := Ping(os.Args[2], os.Args[3], os.Args[4])
+		if err != nil {
+			fmt.Printf("Error: %s\n", err)
+		}
 	case "load":
 		if len(os.Args) < 3 {
 			fmt.Println("Error: Tar file path required for load")
@@ -334,6 +343,7 @@ func printUsage() {
 	fmt.Println("  basic-docker network-delete <network-id>   Delete a network by ID")
 	fmt.Println("  basic-docker network-attach <network-id> <container-id> Attach a container to a network")
 	fmt.Println("  basic-docker network-detach <network-id> <container-id> Detach a container from a network")
+	fmt.Println("  basic-docker network-ping <network-id> <source-container-id> <target-container-id> Test connectivity between containers")
 	fmt.Println("  basic-docker load <tar-file-path>          Load an image from a tar file")
 	fmt.Println("  basic-docker image rm <image-name>         Remove an image by name")
 }

main_test.go

@@ -305,4 +305,47 @@ func BenchmarkVolumeAttachment(b *testing.B) {
 			b.Fatalf("Volume not found: %v", err)
 		}
 	}
+}
+
+// TestNetworkPingCLI tests the network-ping CLI command functionality
+func TestNetworkPingCLI(t *testing.T) {
+	// Cleanup: Ensure no existing networks interfere with the test
+	networks = []Network{}
+	saveNetworks()
+
+	// Setup: Create a network and attach two containers
+	networkName := "test-cli-network"
+	CreateNetwork(networkName)
+	networkID := networks[0].ID
+
+	container1 := "cli-container-1"
+	container2 := "cli-container-2"
+
+	err := AttachContainerToNetwork(networkID, container1)
+	if err != nil {
+		t.Fatalf("Failed to attach container 1: %v", err)
+	}
+
+	err = AttachContainerToNetwork(networkID, container2)
+	if err != nil {
+		t.Fatalf("Failed to attach container 2: %v", err)
+	}
+
+	// Test successful ping - this directly tests the CLI function call
+	err = Ping(networkID, container1, container2)
+	if err != nil {
+		t.Errorf("CLI ping failed for containers in same network: %v", err)
+	}
+
+	// Test ping with non-existent container
+	err = Ping(networkID, container1, "non-existent-container")
+	if err == nil {
+		t.Errorf("Expected CLI ping to fail for non-existent container, but it succeeded")
+	}
+
+	// Test ping with non-existent network
+	err = Ping("non-existent-network", container1, container2)
+	if err == nil {
+		t.Errorf("Expected CLI ping to fail for non-existent network, but it succeeded")
+	}
 }