Add unit tests for combinedConfigFiles logic ✅

Signed-off-by: Vedant Koditkar <vedant.koditkar@outlook.com>

pkg/compose/ls_test.go

@@ -17,6 +17,7 @@
 package compose
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/docker/compose/v2/pkg/api"
@@ -66,3 +67,56 @@ func TestStacksMixedStatus(t *testing.T) {
 	assert.Equal(t, combinedStatus([]string{"running", "running", "running"}), "running(3)")
 	assert.Equal(t, combinedStatus([]string{"running", "exited", "running"}), "exited(1), running(2)")
 }
+
+func TestCombinedConfigFiles(t *testing.T) {
+	containersByLabel := map[string][]moby.Container{
+		"project1": {
+			{
+				ID:     "service1",
+				State:  "running",
+				Labels: map[string]string{api.ProjectLabel: "project1", api.ConfigFilesLabel: "/home/docker-compose.yaml"},
+			},
+			{
+				ID:     "service2",
+				State:  "running",
+				Labels: map[string]string{api.ProjectLabel: "project1", api.ConfigFilesLabel: "/home/docker-compose.yaml"},
+			},
+		},
+		"project2": {
+			{
+				ID:     "service3",
+				State:  "running",
+				Labels: map[string]string{api.ProjectLabel: "project2", api.ConfigFilesLabel: "/home/project2-docker-compose.yaml"},
+			},
+		},
+		"project3": {
+			{
+				ID:     "service4",
+				State:  "running",
+				Labels: map[string]string{api.ProjectLabel: "project3"},
+			},
+		},
+	}
+
+	testData := map[string]struct {
+		ConfigFiles string
+		Error       error
+	}{
+		"project1": {ConfigFiles: "/home/docker-compose.yaml", Error: nil},
+		"project2": {ConfigFiles: "/home/project2-docker-compose.yaml", Error: nil},
+		"project3": {ConfigFiles: "", Error: fmt.Errorf("No label %q set on container %q of compose project", api.ConfigFilesLabel, "service4")},
+	}
+
+	for project, containers := range containersByLabel {
+		configFiles, err := combinedConfigFiles(containers)
+
+		expected := testData[project]
+
+		if expected.Error != nil {
+			assert.Equal(t, err.Error(), expected.Error.Error())
+		} else {
+			assert.Equal(t, err, expected.Error)
+		}
+		assert.Equal(t, configFiles, expected.ConfigFiles)
+	}
+}