diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4a14e47c..607d65e7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,6 +8,11 @@ jobs:
   ci:
     name: CI
     runs-on: ubuntu-latest
+    services:
+      mongo:
+        image: mongo:4.4-focal
+        ports:
+          - 27017:27017
     steps:
       - name: set up
         uses: actions/setup-go@v3
@@ -30,6 +35,8 @@ jobs:
           args: --timeout=10m
       - name: test
         run: go test ./... -v -race -coverprofile=coverage.txt -covermode=atomic -timeout 10m
+        env:
+          REEARTH_DB: mongodb://localhost
       - name: Send coverage report
         uses: codecov/codecov-action@v2
         with:
diff --git a/internal/infrastructure/mongo/asset_test.go b/internal/infrastructure/mongo/asset_test.go
new file mode 100644
index 00000000..135683df
--- /dev/null
+++ b/internal/infrastructure/mongo/asset_test.go
@@ -0,0 +1,66 @@
+package mongo
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/reearth/reearth-backend/pkg/asset"
+	"github.com/reearth/reearth-backend/pkg/id"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFindByID(t *testing.T) {
+	tests := []struct {
+		Name     string
+		Expected struct {
+			Name  string
+			Asset *asset.Asset
+		}
+	}{
+		{
+			Expected: struct {
+				Name  string
+				Asset *asset.Asset
+			}{
+				Asset: asset.New().
+					NewID().
+					CreatedAt(time.Now()).
+					Team(id.NewTeamID()).
+					Name("name").
+					Size(10).
+					URL("hxxps://https://reearth.io/").
+					ContentType("json").
+					MustBuild(),
+			},
+		},
+	}
+
+	initDB := connect(t)
+
+	for _, tc := range tests {
+		tc := tc
+
+		t.Run(tc.Name, func(t *testing.T) {
+			t.Parallel()
+
+			client, dropDB := initDB()
+			defer dropDB()
+
+			repo := NewAsset(client)
+			ctx := context.Background()
+			err := repo.Save(ctx, tc.Expected.Asset)
+			assert.NoError(t, err)
+
+			got, err := repo.FindByID(ctx, tc.Expected.Asset.ID())
+			assert.NoError(t, err)
+			assert.Equal(t, tc.Expected.Asset.ID(), got.ID())
+			assert.Equal(t, tc.Expected.Asset.CreatedAt(), got.CreatedAt())
+			assert.Equal(t, tc.Expected.Asset.Team(), got.Team())
+			assert.Equal(t, tc.Expected.Asset.URL(), got.URL())
+			assert.Equal(t, tc.Expected.Asset.Size(), got.Size())
+			assert.Equal(t, tc.Expected.Asset.Name(), got.Name())
+			assert.Equal(t, tc.Expected.Asset.ContentType(), got.ContentType())
+		})
+	}
+}
diff --git a/internal/infrastructure/mongo/mongo_test.go b/internal/infrastructure/mongo/mongo_test.go
new file mode 100644
index 00000000..ec132989
--- /dev/null
+++ b/internal/infrastructure/mongo/mongo_test.go
@@ -0,0 +1,43 @@
+package mongo
+
+import (
+	"context"
+	"encoding/hex"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/reearth/reearth-backend/internal/infrastructure/mongo/mongodoc"
+	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/uuid"
+)
+
+func connect(t *testing.T) func() (*mongodoc.Client, func()) {
+	t.Helper()
+
+	// Skip unit testing if "REEARTH_DB" is not configured
+	// See details: https://github.com/reearth/reearth/issues/273
+	db := os.Getenv("REEARTH_DB")
+	if db == "" {
+		t.SkipNow()
+		return nil
+	}
+
+	c, _ := mongo.Connect(
+		context.Background(),
+		options.Client().
+			ApplyURI(db).
+			SetConnectTimeout(time.Second*10),
+	)
+
+	return func() (*mongodoc.Client, func()) {
+		database, _ := uuid.New()
+		databaseName := "reearth-test-" + hex.EncodeToString(database[:])
+		client := mongodoc.NewClient(databaseName, c)
+
+		return client, func() {
+			_ = c.Database(databaseName).Drop(context.Background())
+		}
+	}
+}