Add more unit tests and logging

Author: dhurley

internal/file/file_manager_service.go

@@ -386,6 +386,7 @@ func (fms *FileManagerService) DetermineFileActions(
 		// If file currently exists on disk, is being tracked in manifest and file hash is different.
 		// Treat it as a file update.
 		if ok && modifiedFile.File.GetFileMeta().GetHash() != currentFile.GetFileMeta().GetHash() {
+			slog.DebugContext(ctx, "Tracked file requires updating", "file_name", fileName)
 			modifiedFile.Action = model.Update
 			fileDiff[fileName] = modifiedFile
 
@@ -395,6 +396,7 @@ func (fms *FileManagerService) DetermineFileActions(
 		// If file doesn't exist on disk.
 		// Treat it as adding a new file.
 		if fileStats, statErr := os.Stat(fileName); errors.Is(statErr, os.ErrNotExist) {
+			slog.DebugContext(ctx, "New untracked file to created", "file_name", fileName)
 			modifiedFile.Action = model.Add
 			fileDiff[fileName] = modifiedFile
 
@@ -415,6 +417,7 @@ func (fms *FileManagerService) DetermineFileActions(
 			}
 
 			if metadataOfFileOnDisk.GetHash() != modifiedFile.File.GetFileMeta().GetHash() {
+				slog.DebugContext(ctx, "Untracked file requires updating", "file_name", fileName)
 				modifiedFile.Action = model.Update
 				fileDiff[fileName] = modifiedFile
 			}

internal/file/file_manager_service_test.go

@@ -805,6 +805,24 @@ func TestFileManagerService_DetermineFileActions(t *testing.T) {
 			expectedContent: make(map[string][]byte),
 			expectedError:   nil,
 		},
+		{
+			name:        "Test 4: File is actually a directory",
+			allowedDirs: []string{tempDir},
+			modifiedFiles: map[string]*model.FileCache{
+				tempDir: {
+					File: &mpi.File{
+						FileMeta: protos.FileMeta(tempDir, files.GenerateHash(fileContent)),
+					},
+				},
+			},
+			currentFiles:    make(map[string]*mpi.File),
+			expectedCache:   map[string]*model.FileCache(nil),
+			expectedContent: make(map[string][]byte),
+			expectedError: fmt.Errorf(
+				"unable to create file %s since a directory with the same name already exists on the data plane",
+				tempDir,
+			),
+		},
 	}
 
 	for _, test := range tests {
@@ -828,7 +846,13 @@ func TestFileManagerService_DetermineFileActions(t *testing.T) {
 				test.currentFiles,
 				test.modifiedFiles,
 			)
-			require.NoError(tt, fileActionErr)
+
+			if test.expectedError != nil {
+				require.EqualError(tt, fileActionErr, test.expectedError.Error())
+			} else {
+				require.NoError(tt, fileActionErr)
+			}
+
 			assert.Equal(tt, test.expectedCache, diff)
 		})
 	}