Add comprehensive test coverage for core functionalities

This commit introduces test cases for the API, archive, store, and filesystem functionalities, as well as a functional test for a full workflow. It ensures robust testing for snapshot operations, archiving, and blob management, significantly improving reliability.

hash/hash_test.go

@@ -0,0 +1,95 @@
+package hash
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestCalculateFileHash(t *testing.T) {
+	// Create a temporary directory for tests
+	tempDir, err := os.MkdirTemp("", "agate-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp directory: %v", err)
+	}
+	defer os.RemoveAll(tempDir) // Clean up after test
+
+	// Create a test file with known content
+	testContent := "This is a test file for hashing"
+	testFilePath := filepath.Join(tempDir, "test_file.txt")
+	if err := os.WriteFile(testFilePath, []byte(testContent), 0644); err != nil {
+		t.Fatalf("Failed to create test file: %v", err)
+	}
+
+	// Calculate the expected hash manually
+	hasher := sha256.New()
+	hasher.Write([]byte(testContent))
+	expectedHash := hex.EncodeToString(hasher.Sum(nil))
+
+	// Calculate the hash using the function
+	hash, err := CalculateFileHash(testFilePath)
+	if err != nil {
+		t.Fatalf("Failed to calculate file hash: %v", err)
+	}
+
+	// Check that the hash matches the expected value
+	if hash != expectedHash {
+		t.Errorf("Hash does not match: got %s, want %s", hash, expectedHash)
+	}
+
+	// Test with a non-existent file
+	_, err = CalculateFileHash(filepath.Join(tempDir, "nonexistent.txt"))
+	if err == nil {
+		t.Fatalf("Expected error when calculating hash of non-existent file, got nil")
+	}
+
+	// Test with a directory
+	dirPath := filepath.Join(tempDir, "test_dir")
+	if err := os.MkdirAll(dirPath, 0755); err != nil {
+		t.Fatalf("Failed to create test directory: %v", err)
+	}
+	_, err = CalculateFileHash(dirPath)
+	if err == nil {
+		t.Fatalf("Expected error when calculating hash of a directory, got nil")
+	}
+
+	// Test with an empty file
+	emptyFilePath := filepath.Join(tempDir, "empty_file.txt")
+	if err := os.WriteFile(emptyFilePath, []byte{}, 0644); err != nil {
+		t.Fatalf("Failed to create empty test file: %v", err)
+	}
+	emptyHash, err := CalculateFileHash(emptyFilePath)
+	if err != nil {
+		t.Fatalf("Failed to calculate hash of empty file: %v", err)
+	}
+	// The SHA-256 hash of an empty string is e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
+	expectedEmptyHash := "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+	if emptyHash != expectedEmptyHash {
+		t.Errorf("Empty file hash does not match: got %s, want %s", emptyHash, expectedEmptyHash)
+	}
+
+	// Test with a large file
+	largeFilePath := filepath.Join(tempDir, "large_file.bin")
+	largeFileSize := 1024 * 1024 // 1 MB
+	largeFile, err := os.Create(largeFilePath)
+	if err != nil {
+		t.Fatalf("Failed to create large test file: %v", err)
+	}
+	// Fill the file with a repeating pattern
+	pattern := []byte("0123456789")
+	for i := 0; i < largeFileSize/len(pattern); i++ {
+		if _, err := largeFile.Write(pattern); err != nil {
+			largeFile.Close()
+			t.Fatalf("Failed to write to large test file: %v", err)
+		}
+	}
+	largeFile.Close()
+
+	// Calculate the hash of the large file
+	_, err = CalculateFileHash(largeFilePath)
+	if err != nil {
+		t.Fatalf("Failed to calculate hash of large file: %v", err)
+	}
+}