diff --git a/pkg/test/storage_test.go b/pkg/test/storage_test.go
new file mode 100644
index 0000000..08a1994
--- /dev/null
+++ b/pkg/test/storage_test.go
@@ -0,0 +1,144 @@
+package test_test
+
+import (
+	"fmt"
+	"net/mail"
+	"reflect"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/inbucket/inbucket/v3/pkg/extension/event"
+	"github.com/inbucket/inbucket/v3/pkg/message"
+	"github.com/inbucket/inbucket/v3/pkg/storage"
+	"github.com/inbucket/inbucket/v3/pkg/test"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var testMessageIDSource uint32
+
+func TestStoreStubRemoveMessage(t *testing.T) {
+	ss := test.NewStore()
+
+	// Add messages.
+	inputMsgs := make([]*message.Delivery, 5)
+	for i := range inputMsgs {
+		subject := fmt.Sprintf("%s message %v", "box1", i)
+		inputMsgs[i] = makeTestMessage("box1", subject)
+		id, err := ss.AddMessage(inputMsgs[i])
+		require.NoError(t, err)
+		require.NotEmpty(t, id, "AddMessage() must return an ID")
+	}
+
+	// Delete second message.
+	deleted := inputMsgs[1]
+	err := ss.RemoveMessage("box1", deleted.ID())
+	assert.NoError(t, err, "DeleteMessage must not fail")
+
+	// Verify message is not in mailbox.
+	messages, err := ss.GetMessages("box1")
+	assert.NoError(t, err)
+	assert.NotContains(t, messages, deleted, "Mailbox should not contain msg %q", deleted.ID())
+
+	// Verify message is no longer retrievable.
+	got, err := ss.GetMessage("box1", deleted.ID())
+	assert.Error(t, err)
+	assert.Nil(t, got, "Message should have been nil")
+
+	// Verify message is in deleted list.
+	assert.True(t, ss.MessageDeleted(deleted), "Message %q should be in deleted list", deleted.ID())
+}
+
+func TestStoreStubMailboxAddGetVisit(t *testing.T) {
+	ss := test.NewStore()
+
+	tcs := []struct {
+		mailbox string
+		count   int
+	}{
+		{mailbox: "box1", count: 1},
+		{mailbox: "box2", count: 1},
+		{mailbox: "box3", count: 3},
+	}
+	for _, tc := range tcs {
+		tc := tc
+		t.Run(tc.mailbox, func(t *testing.T) {
+			var err error
+
+			// Add messages.
+			inputMsgs := make([]*message.Delivery, tc.count)
+			for i := range inputMsgs {
+				subject := fmt.Sprintf("%s message %v", tc.mailbox, i)
+				inputMsgs[i] = makeTestMessage(tc.mailbox, subject)
+				id, err := ss.AddMessage(inputMsgs[i])
+				require.NoError(t, err)
+				require.NotEmpty(t, id, "AddMessage() must return an ID")
+			}
+
+			// Verify entire mailbox contents.
+			gotMsgs, err := ss.GetMessages(tc.mailbox)
+			require.NoError(t, err, "GetMessages() should not error")
+			require.NoError(t, err)
+			assert.Len(t, gotMsgs, tc.count, "GetMessages() returned wrong number of items")
+			for _, want := range inputMsgs {
+				assert.Contains(t, gotMsgs, want, "GetMessages() did not return expected message")
+			}
+
+			// Fetch and verify individual messages.
+			for _, want := range inputMsgs {
+				got, err := ss.GetMessage(tc.mailbox, want.ID())
+				require.NoError(t, err, "GetMessage() should not error")
+				assert.Equal(t, want, got, "GetMessage() returned unexpected value")
+			}
+		})
+	}
+
+	t.Run("VisitMailboxes counts", func(t *testing.T) {
+		expectCounts := make(map[string]int, len(tcs))
+		for _, tc := range tcs {
+			expectCounts[tc.mailbox] = tc.count
+		}
+
+		// Verify message count of each visited mailbox.
+		err := ss.VisitMailboxes(func(m []storage.Message) (cont bool) {
+			require.NotEmpty(t, m, "Visitor called with empty message slice")
+			mailbox := m[0].Mailbox()
+
+			want, ok := expectCounts[mailbox]
+			assert.True(t, ok, "Mailbox %q was unexpected", mailbox)
+			assert.Equal(t, want, len(m), "Unexpected message count for mailbox %q", mailbox)
+
+			delete(expectCounts, mailbox)
+
+			return true
+		})
+		require.NoError(t, err, "VisitMailboxes() must not fail")
+
+		// Verify all mailboxes were visited.
+		assert.Empty(t, expectCounts, "Failed to visit mailboxes: %v",
+			reflect.ValueOf(expectCounts).MapKeys())
+	})
+}
+
+func makeTestMessage(mailbox string, subject string) *message.Delivery {
+	id := fmt.Sprintf("%06d", atomic.AddUint32(&testMessageIDSource, 1))
+	from := mail.Address{Name: "From Test", Address: "from@example.com"}
+	to := mail.Address{Name: "To Test", Address: "to@example.com"}
+
+	return &message.Delivery{
+		Meta: event.MessageMetadata{
+			ID:      id,
+			Mailbox: mailbox,
+			From:    &from,
+			To:      []*mail.Address{&to},
+			Date:    time.Now(),
+			Subject: subject,
+		},
+		Reader: strings.NewReader(fmt.Sprintf(
+			"From: %s\nTo: %s\nSubject: %s\n\nTest message about %q\n",
+			from, to, subject, subject,
+		)),
+	}
+}