test(theming): cover background file picker mime filtering

apps/theming/src/components/UserSectionBackground.spec.ts

@@ -0,0 +1,86 @@
+/*!
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { shallowMount } from '@vue/test-utils'
+import { describe, expect, it, vi } from 'vitest'
+import UserSectionBackground from './UserSectionBackground.vue'
+
+const allowDirectories = vi.hoisted(() => vi.fn<(allow: boolean) => unknown>())
+const setMimeTypeFilter = vi.hoisted(() => vi.fn<(mimes: string[]) => unknown>())
+
+vi.mock('@nextcloud/dialogs', () => ({
+	getFilePickerBuilder: vi.fn(() => {
+		const builder = {
+			allowDirectories,
+			setMimeTypeFilter,
+			setMultiSelect: vi.fn(),
+			addButton: vi.fn(),
+			build: vi.fn(),
+		}
+
+		builder.allowDirectories.mockReturnValue(builder)
+		builder.setMimeTypeFilter.mockReturnValue(builder)
+		builder.setMultiSelect.mockReturnValue(builder)
+		builder.addButton.mockReturnValue(builder)
+		builder.build.mockReturnValue({
+			pick: vi.fn().mockResolvedValue(undefined),
+		})
+
+		return builder
+	}),
+}))
+
+vi.mock('@nextcloud/initial-state', () => ({
+	loadState: vi.fn((_app: string, key: string) => {
+		switch (key) {
+		case 'shippedBackgrounds':
+			return {}
+		case 'themingDefaults':
+			return {
+				backgroundImage: '',
+				backgroundColor: '#ffffff',
+				backgroundMime: '',
+				defaultShippedBackground: '',
+			}
+		case 'data':
+			return {
+				backgroundImage: '',
+				backgroundColor: '#ffffff',
+				backgroundMime: '',
+			}
+		case 'userBackgroundImage':
+			return 'default'
+		default:
+			throw new Error(`Unexpected initial state key: ${key}`)
+		}
+	}),
+}))
+
+vi.mock('@nextcloud/l10n', () => ({
+	t: (_app: string, text: string) => text,
+}))
+
+describe('UserSectionBackground', () => {
+	it('opens the picker filtered to images while keeping folders navigable', async () => {
+		const wrapper = shallowMount(UserSectionBackground, {
+			global: {
+				stubs: {
+					NcSettingsSection: {
+						template: '<section><slot /></section>',
+					},
+				},
+			},
+		})
+
+		await wrapper.get('button[aria-label="Custom background"]').trigger('click')
+
+		// A mime-type filter keeps folders visible for navigation while
+		// restricting pickable entries to images. Regression guard for the
+		// empty file dialog caused by a node filter that also hid folders.
+		expect(setMimeTypeFilter).toHaveBeenCalledOnce()
+		expect(setMimeTypeFilter).toHaveBeenCalledWith(['image/*'])
+		expect(allowDirectories).toHaveBeenCalledWith(false)
+	})
+})