feat(depot): backend interface and local backend

Implement Backend interface with Probe/Get/Put methods, ProbeState constants, and LocalBackend using filesystem storage with atomic operations and hash verification. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-04 23:37:13 +02:00
parent f1ff144740
commit da59e54261
3 changed files with 276 additions and 0 deletions
@@ -0,0 +1,139 @@
+package depot
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLocalRoundTrip(t *testing.T) {
+	tmpDir := t.TempDir()
+	backend := &LocalBackend{Root: tmpDir}
+
+	// Generate test data
+	testData := []byte("hello world")
+	testSHA := fmt.Sprintf("%x", sha256.Sum256(testData))
+
+	// Create source file
+	srcFile := filepath.Join(tmpDir, "source.txt")
+	if err := os.WriteFile(srcFile, testData, 0644); err != nil {
+		t.Fatalf("failed to create source file: %v", err)
+	}
+
+	// Put
+	ctx := context.Background()
+	if err := backend.Put(ctx, testSHA, srcFile); err != nil {
+		t.Fatalf("Put failed: %v", err)
+	}
+
+	// Probe should be Present
+	state, transient, err := backend.Probe(ctx, testSHA)
+	if err != nil {
+		t.Fatalf("Probe failed: %v", err)
+	}
+	if state != Present {
+		t.Fatalf("expected Present, got %v", state)
+	}
+	if transient {
+		t.Fatalf("local backend should never be transient")
+	}
+
+	// Get
+	destFile := filepath.Join(tmpDir, "dest.txt")
+	if err := backend.Get(ctx, testSHA, destFile); err != nil {
+		t.Fatalf("Get failed: %v", err)
+	}
+
+	// Verify bytes match
+	gotData, err := os.ReadFile(destFile)
+	if err != nil {
+		t.Fatalf("failed to read dest file: %v", err)
+	}
+	if !bytes.Equal(gotData, testData) {
+		t.Fatalf("data mismatch: want %s, got %s", testData, gotData)
+	}
+}
+
+func TestLocalProbeAbsent(t *testing.T) {
+	tmpDir := t.TempDir()
+	backend := &LocalBackend{Root: tmpDir}
+
+	ctx := context.Background()
+	state, transient, err := backend.Probe(ctx, "0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d")
+	if err != nil {
+		t.Fatalf("Probe should not error on missing blob: %v", err)
+	}
+	if state != Absent {
+		t.Fatalf("expected Absent, got %v", state)
+	}
+	if transient {
+		t.Fatalf("local backend should never be transient")
+	}
+}
+
+func TestLocalGetHashMismatch(t *testing.T) {
+	tmpDir := t.TempDir()
+	backend := &LocalBackend{Root: tmpDir}
+
+	// Create a corrupt blob at the expected path
+	sha := "0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d0b1d"
+	blobKey := BlobKey(sha)
+	blobPath := filepath.Join(tmpDir, blobKey)
+
+	if err := os.MkdirAll(filepath.Dir(blobPath), 0755); err != nil {
+		t.Fatalf("failed to create blob dir: %v", err)
+	}
+	if err := os.WriteFile(blobPath, []byte("wrong data"), 0644); err != nil {
+		t.Fatalf("failed to create blob file: %v", err)
+	}
+
+	// Get should error
+	ctx := context.Background()
+	destFile := filepath.Join(tmpDir, "dest.txt")
+	err := backend.Get(ctx, sha, destFile)
+	if err == nil {
+		t.Fatalf("Get should error on hash mismatch")
+	}
+
+	// Destination file should not exist
+	_, err = os.Stat(destFile)
+	if !os.IsNotExist(err) {
+		t.Fatalf("dest file should not exist after Get error: %v", err)
+	}
+}
+
+func TestLocalPutIdempotent(t *testing.T) {
+	tmpDir := t.TempDir()
+	backend := &LocalBackend{Root: tmpDir}
+
+	testData := []byte("hello world")
+	testSHA := fmt.Sprintf("%x", sha256.Sum256(testData))
+
+	srcFile := filepath.Join(tmpDir, "source.txt")
+	if err := os.WriteFile(srcFile, testData, 0644); err != nil {
+		t.Fatalf("failed to create source file: %v", err)
+	}
+
+	ctx := context.Background()
+
+	// Put twice
+	if err := backend.Put(ctx, testSHA, srcFile); err != nil {
+		t.Fatalf("first Put failed: %v", err)
+	}
+	if err := backend.Put(ctx, testSHA, srcFile); err != nil {
+		t.Fatalf("second Put failed: %v", err)
+	}
+
+	// Verify blob exists
+	state, _, err := backend.Probe(ctx, testSHA)
+	if err != nil {
+		t.Fatalf("Probe failed: %v", err)
+	}
+	if state != Present {
+		t.Fatalf("expected Present after Put, got %v", state)
+	}
+}