feat: add booster eligibility role and logging functionality

- Added BOOSTER_ELIGIBILITY_ROLE_ID and LOG_LEVEL to .env.example and README.md
- Updated GitHub Actions workflow to include new environment variables
- Enhanced configuration loading to support booster eligibility role
- Implemented role checking logic in bot handlers and guild member updates
- Introduced logging using Winston for better traceability of actions
- Created tests for guild member update handling to ensure correct role removal
- Refactored DiscordRoleRepository to simplify role position resolution

src/discord/events/guildMemberUpdate.test.ts

@@ -0,0 +1,36 @@
+import { describe, expect, test } from "bun:test";
+import { handleGuildMemberUpdate } from "./guildMemberUpdate";
+
+class FakeService {
+  removed: Array<{ guildId: string; userId: string }> = [];
+
+  async removeRoleForLostBoost(input: { guildId: string; userId: string }): Promise<void> {
+    this.removed.push(input);
+  }
+}
+
+function member(hasRole: boolean) {
+  return {
+    id: "user",
+    guild: { id: "guild" },
+    roles: { cache: { has: (roleId: string) => roleId === "booster-role" && hasRole } }
+  };
+}
+
+describe("handleGuildMemberUpdate", () => {
+  test("removes custom role when booster eligibility role is removed", async () => {
+    const service = new FakeService();
+
+    await handleGuildMemberUpdate(member(true), member(false), service, "booster-role");
+
+    expect(service.removed).toEqual([{ guildId: "guild", userId: "user" }]);
+  });
+
+  test("does nothing while booster eligibility role remains", async () => {
+    const service = new FakeService();
+
+    await handleGuildMemberUpdate(member(true), member(true), service, "booster-role");
+
+    expect(service.removed).toEqual([]);
+  });
+});

src/discord/events/guildMemberUpdate.ts

@@ -1,16 +1,23 @@
-import type { BoosterRoleService } from "../../services/boosterRoleService";
-
 type GuildMemberLike = {
   id: string;
-  premiumSince: Date | null;
   guild: { id: string };
+  roles: { cache: { has(roleId: string): boolean } };
 };
 
-export async function handleGuildMemberUpdate(oldMember: GuildMemberLike, newMember: GuildMemberLike, service: BoosterRoleService): Promise<void> {
-  const hadBoost = Boolean(oldMember.premiumSince);
-  const hasBoost = Boolean(newMember.premiumSince);
+type BoosterRoleRemovalService = {
+  removeRoleForLostBoost(input: { guildId: string; userId: string }): Promise<void>;
+};
 
-  if (hadBoost && !hasBoost) {
+export async function handleGuildMemberUpdate(
+  oldMember: GuildMemberLike,
+  newMember: GuildMemberLike,
+  service: BoosterRoleRemovalService,
+  boosterEligibilityRoleId: string
+): Promise<void> {
+  const hadBoosterRole = oldMember.roles.cache.has(boosterEligibilityRoleId);
+  const hasBoosterRole = newMember.roles.cache.has(boosterEligibilityRoleId);
+
+  if (hadBoosterRole && !hasBoosterRole) {
     await service.removeRoleForLostBoost({ guildId: newMember.guild.id, userId: newMember.id });
   }
 }