feat(app): gate a collapsing guild header behind an experiment (#2779)

fluxer_app/src/features/app/state/GuildHeaderCollapseRollout.test.ts

@@ -0,0 +1,95 @@
+// @vitest-environment happy-dom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {
+	type ExperimentAssignmentsResponse,
+	INERT_EXPERIMENT_ASSIGNMENTS_RESPONSE,
+} from '@fluxer/schema/src/domains/experiment/ExperimentSchemas';
+import {
+	type GuildHeaderCollapseAssignmentResponse,
+	INERT_GUILD_HEADER_COLLAPSE_ASSIGNMENT,
+} from '@fluxer/schema/src/domains/experiment/GuildHeaderCollapseSchemas';
+import {runInAction} from 'mobx';
+import {afterEach, describe, expect, it, vi} from 'vitest';
+
+vi.mock('@app/features/platform/utils/AppLogger', () => ({
+	Logger: class {
+		debug = vi.fn();
+		info = vi.fn();
+		warn = vi.fn();
+		error = vi.fn();
+	},
+}));
+
+vi.mock('@app/features/platform/transport/RestTransport', () => ({
+	http: {get: vi.fn(), post: vi.fn()},
+}));
+
+const {ExperimentAssignments} = await import('@app/features/experiment/state/ExperimentAssignments');
+const {GuildHeaderCollapseRollout} = await import('@app/features/app/state/GuildHeaderCollapseRollout');
+
+const TARGETED_ASSIGNMENT: GuildHeaderCollapseAssignmentResponse = {
+	enabled: true,
+	config_version: 3,
+	user_targeted: true,
+	source: 'canary',
+};
+
+function publish(assignment: GuildHeaderCollapseAssignmentResponse | undefined): void {
+	const response: ExperimentAssignmentsResponse = {
+		poll_interval_seconds: 300,
+		poll_jitter_percent: 15,
+		assignments: assignment === undefined ? {} : {guild_header_collapse: assignment},
+	};
+	runInAction(() => {
+		ExperimentAssignments.response = response;
+	});
+}
+
+afterEach(() => {
+	runInAction(() => {
+		ExperimentAssignments.response = INERT_EXPERIMENT_ASSIGNMENTS_RESPONSE;
+	});
+});
+
+describe('GuildHeaderCollapseRollout', () => {
+	it('reads the inert assignment before any response has landed', () => {
+		expect(GuildHeaderCollapseRollout.assignment).toEqual(INERT_GUILD_HEADER_COLLAPSE_ASSIGNMENT);
+		expect(GuildHeaderCollapseRollout.collapsesOnScroll).toBe(false);
+	});
+
+	it('treats a missing experiment key as off', () => {
+		publish(undefined);
+
+		expect(GuildHeaderCollapseRollout.assignment).toEqual(INERT_GUILD_HEADER_COLLAPSE_ASSIGNMENT);
+		expect(GuildHeaderCollapseRollout.collapsesOnScroll).toBe(false);
+	});
+
+	it('collapses on scroll for a targeted account', () => {
+		publish(TARGETED_ASSIGNMENT);
+
+		expect(GuildHeaderCollapseRollout.assignment).toEqual(TARGETED_ASSIGNMENT);
+		expect(GuildHeaderCollapseRollout.collapsesOnScroll).toBe(true);
+	});
+
+	it('keeps the old header for an account outside the rollout', () => {
+		publish({...TARGETED_ASSIGNMENT, user_targeted: false, source: null});
+
+		expect(GuildHeaderCollapseRollout.collapsesOnScroll).toBe(false);
+	});
+
+	it('keeps the old header while the rollout is disabled instance-wide', () => {
+		publish({...TARGETED_ASSIGNMENT, enabled: false});
+
+		expect(GuildHeaderCollapseRollout.collapsesOnScroll).toBe(false);
+	});
+
+	it('follows a later poll that turns the rollout off', () => {
+		publish(TARGETED_ASSIGNMENT);
+		expect(GuildHeaderCollapseRollout.collapsesOnScroll).toBe(true);
+
+		publish({...TARGETED_ASSIGNMENT, enabled: false, user_targeted: false, source: null});
+
+		expect(GuildHeaderCollapseRollout.collapsesOnScroll).toBe(false);
+	});
+});

fluxer_app/src/features/app/state/GuildHeaderCollapseRollout.ts

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+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import ExperimentAssignments from '@app/features/experiment/state/ExperimentAssignments';
+import {readGuildHeaderCollapseAssignment} from '@fluxer/schema/src/domains/experiment/ExperimentSchemas';
+import {
+	type GuildHeaderCollapseAssignmentResponse,
+	isGuildHeaderCollapseTargeted,
+} from '@fluxer/schema/src/domains/experiment/GuildHeaderCollapseSchemas';
+
+class GuildHeaderCollapseRolloutSelector {
+	get assignment(): GuildHeaderCollapseAssignmentResponse {
+		return readGuildHeaderCollapseAssignment(ExperimentAssignments.response);
+	}
+
+	get collapsesOnScroll(): boolean {
+		return isGuildHeaderCollapseTargeted(this.assignment);
+	}
+}
+
+export const GuildHeaderCollapseRollout = new GuildHeaderCollapseRolloutSelector();
+
+export default GuildHeaderCollapseRollout;