Add focused unit tests for libvirt image management

Implements comprehensive yet focused unit tests for the inMemoryImage
implementation in the libvirt provider.

Tests cover:
- Image creation from byte arrays (text, empty, binary data)
- Size calculation functionality
- String representation
- Import operations with success and error handling

The test suite uses table-driven tests for maintainability and focuses
on testing our wrapper logic rather than Go's standard library behavior.

Test coverage:
- TestInMemoryImage: Validates creation, size(), and string() methods
- TestInMemoryImageImport: Tests importImage with various scenarios

Signed-off-by: Chathurya Adapa <Adapa.Chathurya1@ibm.com>
Assisted-by: IBM Bob <noreply@ibm.com>

Author: chathuryaadapa

src/cloud-providers/libvirt/image_test.go

@@ -0,0 +1,116 @@
+// (C) Copyright Confidential Containers Contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package libvirt
+
+import (
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	libvirtxml "libvirt.org/go/libvirtxml"
+)
+
+const (
+	testVolumeName = "test-volume"
+)
+
+// TestInMemoryImage tests the core functionality of inMemoryImage
+func TestInMemoryImage(t *testing.T) {
+	tests := []struct {
+		name string
+		data []byte
+	}{
+		{
+			name: "text data",
+			data: []byte("test image data"),
+		},
+		{
+			name: "empty data",
+			data: []byte{},
+		},
+		{
+			name: "binary data",
+			data: []byte{0x00, 0x01, 0x02, 0xFF, 0xFE, 0xFD},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Test creation
+			img, err := newImageFromBytes(tt.data)
+			require.NoError(t, err)
+			assert.NotNil(t, img)
+
+			// Test size()
+			size, err := img.size()
+			require.NoError(t, err)
+			assert.Equal(t, uint64(len(tt.data)), size)
+
+			// Test string()
+			str := img.string()
+			assert.Contains(t, str, "plain bytes")
+			assert.Contains(t, str, "[")
+			assert.Contains(t, str, "]")
+		})
+	}
+}
+
+// TestInMemoryImageImport tests the importImage functionality
+func TestInMemoryImageImport(t *testing.T) {
+	tests := []struct {
+		name        string
+		data        []byte
+		expectError bool
+		copierFunc  func(*[]byte) func(io.Reader) error
+		validate    func(*testing.T, []byte, []byte)
+	}{
+		{
+			name: "successful import",
+			data: []byte("test data"),
+			copierFunc: func(captured *[]byte) func(io.Reader) error {
+				return func(rdr io.Reader) error {
+					data, err := io.ReadAll(rdr)
+					*captured = data
+					return err
+				}
+			},
+			validate: func(t *testing.T, expected, actual []byte) {
+				assert.Equal(t, expected, actual)
+			},
+		},
+		{
+			name: "copier error",
+			data: []byte("test data"),
+			copierFunc: func(captured *[]byte) func(io.Reader) error {
+				return func(rdr io.Reader) error {
+					return assert.AnError
+				}
+			},
+			expectError: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			img, err := newImageFromBytes(tt.data)
+			require.NoError(t, err)
+
+			var capturedData []byte
+			copier := tt.copierFunc(&capturedData)
+
+			volumeDef := libvirtxml.StorageVolume{Name: testVolumeName}
+			err = img.importImage(copier, volumeDef)
+
+			if tt.expectError {
+				assert.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				if tt.validate != nil {
+					tt.validate(t, tt.data, capturedData)
+				}
+			}
+		})
+	}
+}