feat(testing): add unit tests for file package (#757)

dangazineu · web-flow · commit e370eacb2dd6 · 2025-07-07T10:21:20.000+01:00
This change introduces unit tests for the `file.go` file in the `internal/librarian` package. The tests cover the following functions: - `readAllBytesFromFile` - `appendToFile` - `createAndWriteToFile` - `createAndWriteBytesToFile` The tests use a table-driven approach to test multiple scenarios, including success, error, and edge cases. Fixes: #740
diff --git a/internal/librarian/file_test.go b/internal/librarian/file_test.go
@@ -0,0 +1,185 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package librarian
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func setupTestFile(t *testing.T, content []byte, createDir bool) string {
+	t.Helper()
+	tempDir := t.TempDir()
+	filePath := filepath.Join(tempDir, "test.txt")
+	if !createDir {
+		filePath = filepath.Join(tempDir, "non-existent-dir", "test.txt")
+	}
+	if content != nil {
+		if err := os.WriteFile(filePath, content, 0644); err != nil {
+			t.Fatalf("WriteFile() error = %v", err)
+		}
+	}
+	return filePath
+}
+
+func TestReadAllBytesFromFile(t *testing.T) {
+	t.Parallel()
+	testCases := []struct {
+		name    string
+		content []byte
+		wantErr bool
+	}{
+		{"success", []byte("hello world"), false},
+		{"empty file", []byte(""), false},
+		{"non-existent file", nil, true},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			filePath := setupTestFile(t, tc.content, true)
+
+			got, err := readAllBytesFromFile(filePath)
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("readAllBytesFromFile() error = %v, wantErr %v", err, tc.wantErr)
+			}
+
+			if !tc.wantErr {
+				if diff := cmp.Diff(tc.content, got); diff != "" {
+					t.Errorf("readAllBytesFromFile() mismatch (-want +got):\n%s", diff)
+				}
+			}
+		})
+	}
+}
+
+func TestAppendToFile(t *testing.T) {
+	t.Parallel()
+	testCases := []struct {
+		name            string
+		initialContent  []byte
+		appendedContent string
+		expectedContent string
+		createDir       bool
+		wantErr         bool
+	}{
+		{"success", []byte("hello"), " world", "hello world", true, false},
+		{"empty initial content", []byte(""), "hello", "hello", true, false},
+		{"empty appended content", []byte("hello"), "", "hello", true, false},
+		{"append to non-existent file", nil, "hello", "hello", true, false},
+		{"non-existent dir", nil, "hello", "", false, true},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			filePath := setupTestFile(t, tc.initialContent, tc.createDir)
+
+			err := appendToFile(filePath, tc.appendedContent)
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("appendToFile() error = %v, wantErr %v", err, tc.wantErr)
+			}
+
+			if !tc.wantErr {
+				got, err := os.ReadFile(filePath)
+				if err != nil {
+					t.Fatalf("ReadFile() error = %v", err)
+				}
+				if string(got) != tc.expectedContent {
+					t.Errorf("appendToFile() got %q, want %q", string(got), tc.expectedContent)
+				}
+			}
+		})
+	}
+}
+
+func TestCreateAndWriteToFile(t *testing.T) {
+	t.Parallel()
+	testCases := []struct {
+		name      string
+		content   string
+		createDir bool
+		wantErr   bool
+	}{
+		{"success", "hello world", true, false},
+		{"empty content", "", true, false},
+		{"non-existent dir", "hello", false, true},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			filePath := setupTestFile(t, nil, tc.createDir)
+
+			err := createAndWriteToFile(filePath, tc.content)
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("createAndWriteToFile() error = %v, wantErr %v", err, tc.wantErr)
+			}
+
+			if !tc.wantErr {
+				got, err := os.ReadFile(filePath)
+				if err != nil {
+					t.Fatalf("ReadFile() error = %v", err)
+				}
+				if string(got) != tc.content {
+					t.Errorf("createAndWriteToFile() got %q, want %q", string(got), tc.content)
+				}
+			}
+		})
+	}
+}
+
+func TestCreateAndWriteBytesToFile(t *testing.T) {
+	t.Parallel()
+	testCases := []struct {
+		name      string
+		content   []byte
+		createDir bool
+		wantErr   bool
+	}{
+		{"success", []byte("hello world"), true, false},
+		{"empty content", []byte(""), true, false},
+		{"non-existent dir", []byte("hello"), false, true},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			filePath := setupTestFile(t, nil, tc.createDir)
+
+			err := createAndWriteBytesToFile(filePath, tc.content)
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("createAndWriteBytesToFile() error = %v, wantErr %v", err, tc.wantErr)
+			}
+
+			if !tc.wantErr {
+				got, err := os.ReadFile(filePath)
+				if err != nil {
+					t.Fatalf("ReadFile() error = %v", err)
+				}
+				if diff := cmp.Diff(tc.content, got); diff != "" {
+					t.Errorf("createAndWriteBytesToFile() mismatch (-want +got):\n%s", diff)
+				}
+			}
+		})
+	}
+}
