diff --git a/internal/worker/persistence/test_support.go b/internal/worker/persistence/test_support.go
new file mode 100644
index 00000000..0aa0debc
--- /dev/null
+++ b/internal/worker/persistence/test_support.go
@@ -0,0 +1,71 @@
+// Package persistence provides the database interface for Flamenco Manager.
+package persistence
+
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+)
+
+// Change this to a filename if you want to run a single test and inspect the
+// resulting database.
+const TestDSN = "file::memory:"
+
+func createTestDB() (db *DB, closer func()) {
+	// Delete the SQLite file if it exists on disk.
+	if _, err := os.Stat(TestDSN); err == nil {
+		if err := os.Remove(TestDSN); err != nil {
+			panic(fmt.Sprintf("unable to remove %s: %v", TestDSN, err))
+		}
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+
+	var err error
+
+	db, err = openDB(ctx, TestDSN)
+	if err != nil {
+		panic(fmt.Sprintf("opening DB: %v", err))
+	}
+
+	err = db.migrate(ctx)
+	if err != nil {
+		panic(fmt.Sprintf("migrating DB: %v", err))
+	}
+
+	closer = func() {
+		if err := db.Close(); err != nil {
+			panic(fmt.Sprintf("closing DB: %v", err))
+		}
+	}
+
+	return db, closer
+}
+
+// persistenceTestFixtures creates a test database and returns it and a context.
+// Tests should call the returned cancel function when they're done.
+func persistenceTestFixtures(testContextTimeout time.Duration) (context.Context, context.CancelFunc, *DB) {
+	db, dbCloser := createTestDB()
+
+	var (
+		ctx       context.Context
+		ctxCancel context.CancelFunc
+	)
+	if testContextTimeout > 0 {
+		ctx, ctxCancel = context.WithTimeout(context.Background(), testContextTimeout)
+	} else {
+		ctx = context.Background()
+		ctxCancel = func() {}
+	}
+
+	cancel := func() {
+		ctxCancel()
+		dbCloser()
+	}
+
+	return ctx, cancel, db
+}
diff --git a/internal/worker/persistence/upstream_buffer_test.go b/internal/worker/persistence/upstream_buffer_test.go
new file mode 100644
index 00000000..93a683e2
--- /dev/null
+++ b/internal/worker/persistence/upstream_buffer_test.go
@@ -0,0 +1,104 @@
+package persistence
+
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"projects.blender.org/studio/flamenco/internal/worker/persistence/sqlc"
+	"projects.blender.org/studio/flamenco/pkg/api"
+)
+
+const defaultTimeout = 1 * time.Second
+
+func TestUpstreamBufferQueueEmpty(t *testing.T) {
+	ctx, cancel, db := persistenceTestFixtures(defaultTimeout)
+	defer cancel()
+
+	// Queue should be empty at first.
+	size, err := db.UpstreamBufferQueueSize(ctx)
+	require.NoError(t, err)
+	assert.Zero(t, size)
+
+	// Getting the first queued item on an empty queue should work.
+	first, err := db.UpstreamBufferFrontItem(ctx)
+	require.NoError(t, err)
+	require.Nil(t, first)
+}
+
+func TestUpstreamBufferQueue(t *testing.T) {
+	ctx, cancel, db := persistenceTestFixtures(defaultTimeout)
+	defer cancel()
+
+	// Mock the clock so we can compare 'created at' timestamps.
+	// The database should order by ID anyway, and not by timestamp.
+	fixedNow := db.now()
+	db.nowfunc = func() time.Time { return fixedNow }
+
+	// Queue an update.
+	taskUUID := "3d1e2419-ca9d-4500-bd4f-1e14b5e82947"
+	update1 := api.TaskUpdateJSONRequestBody{
+		Activity:   ptr("Tešt active"),
+		TaskStatus: ptr(api.TaskStatusActive),
+	}
+	require.NoError(t, db.UpstreamBufferQueue(ctx, taskUUID, update1))
+
+	// Queue should have grown.
+	size, err := db.UpstreamBufferQueueSize(ctx)
+	require.NoError(t, err)
+	assert.Equal(t, 1, size)
+
+	// Queue another update.
+	update2 := api.TaskUpdateJSONRequestBody{
+		TaskStatus: ptr(api.TaskStatusCompleted),
+	}
+	require.NoError(t, db.UpstreamBufferQueue(ctx, taskUUID, update2))
+
+	// Queue should have grown again.
+	size, err = db.UpstreamBufferQueueSize(ctx)
+	require.NoError(t, err)
+	assert.Equal(t, 2, size)
+
+	// First update should be at the front of the queue.
+	first, err := db.UpstreamBufferFrontItem(ctx)
+	require.NoError(t, err)
+	{
+		expect := TaskUpdate{
+			TaskUpdate: sqlc.TaskUpdate{
+				ID:        1,
+				CreatedAt: fixedNow,
+				TaskID:    taskUUID,
+				Payload:   []byte(`{"activity":"Tešt active","taskStatus":"active"}`),
+			},
+		}
+		assert.Equal(t, &expect, first)
+	}
+
+	// Deleting should work, and should move the next queued item tot the front of
+	// the queue.
+	require.NoError(t, db.UpstreamBufferDiscard(ctx, first))
+	size, err = db.UpstreamBufferQueueSize(ctx)
+	require.NoError(t, err)
+	assert.Equal(t, 1, size)
+	second, err := db.UpstreamBufferFrontItem(ctx)
+	require.NoError(t, err)
+	{
+		expect := TaskUpdate{
+			TaskUpdate: sqlc.TaskUpdate{
+				ID:        2,
+				CreatedAt: fixedNow,
+				TaskID:    taskUUID,
+				Payload:   []byte(`{"taskStatus":"completed"}`),
+			},
+		}
+		assert.Equal(t, &expect, second)
+	}
+}
+
+func ptr[T any](value T) *T {
+	return &value
+}