storage/blob: Implement usability test using go-imap-backend-tests and go-imap-sql

Blob storage would also benefit from stress
testing and concurrency consistency tests.

But these are things that are probably also
worth adding to go-imap-backend-tests instead.

internal/storage/blob/test_blob.go

@@ -0,0 +1,60 @@
+//+build cgo,!no_sqlite3
+
+package blob
+
+import (
+	"math/rand"
+	"testing"
+
+	backendtests "github.com/foxcpp/go-imap-backend-tests"
+	imapsql "github.com/foxcpp/go-imap-sql"
+	"github.com/foxcpp/maddy/framework/module"
+	imapsql2 "github.com/foxcpp/maddy/internal/storage/imapsql"
+	"github.com/foxcpp/maddy/internal/testutils"
+)
+
+type testBack struct {
+	backendtests.Backend
+	ExtStore module.BlobStore
+}
+
+func TestStore(t *testing.T, newStore func() module.BlobStore, cleanStore func(module.BlobStore)) {
+	// We use go-imap-sql backend and run a subset of
+	// go-imap-backend-tests related to loading and saving messages.
+	//
+	// In the future we should probably switch to using a memory
+	// backend for this.
+
+	backendtests.Whitelist = []string{
+		t.Name() + "/Mailbox_CreateMessage",
+		t.Name() + "/Mailbox_ListMessages_Body",
+		t.Name() + "/Mailbox_CopyMessages",
+		t.Name() + "/Mailbox_Expunge",
+		t.Name() + "/Mailbox_MoveMessages",
+	}
+
+	initBackend := func() backendtests.Backend {
+		randSrc := rand.NewSource(0)
+		prng := rand.New(randSrc)
+		store := newStore()
+
+		b, err := imapsql.New("sqlite3", ":memory:",
+			imapsql2.ExtBlobStore{Base: store}, imapsql.Opts{
+				LazyUpdatesInit: true,
+				PRNG:            prng,
+				Log:             testutils.Logger(t, "imapsql"),
+			},
+		)
+		if err != nil {
+			panic(err)
+		}
+		return testBack{Backend: b, ExtStore: store}
+	}
+	cleanBackend := func(bi backendtests.Backend) {
+		b := bi.(testBack)
+		b.Backend.(*imapsql.Backend).Close()
+		cleanStore(b.ExtStore)
+	}
+
+	backendtests.RunTests(t, initBackend, cleanBackend)
+}