Define adapter interfaces and fake implementations

internal/adapters/storage/fake_test.go

@@ -0,0 +1,31 @@
+package storage
+
+import (
+	"context"
+	"errors"
+	"testing"
+)
+
+func TestFakeBackendCapturesRequestAndReturnsItems(t *testing.T) {
+	fake := &FakeBackend{}
+	req := ArchiveRequest{SessionID: "s1", Items: []ArchiveItem{{Kind: "artifact", LocalPath: "artifacts/log.md"}}}
+
+	res, err := fake.Archive(context.Background(), req)
+	if err != nil {
+		t.Fatalf("Archive() error = %v", err)
+	}
+	if len(fake.Requests) != 1 || fake.Requests[0].SessionID != "s1" {
+		t.Fatalf("requests = %#v, want captured request", fake.Requests)
+	}
+	if len(res.Archived) != 1 {
+		t.Fatalf("archived len = %d, want 1", len(res.Archived))
+	}
+}
+
+func TestFakeBackendError(t *testing.T) {
+	fake := &FakeBackend{Err: errors.New("boom")}
+	_, err := fake.Archive(context.Background(), ArchiveRequest{})
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+}