feat: add optional MongoDB replica deployment (#765)

test/database-connection.test.js

@@ -0,0 +1,38 @@
+require("ts-node/register/transpile-only");
+const { expect } = require("chai");
+
+const config = require("../src/config").default;
+const { getMongoUrl } = require("../src/server/database");
+
+describe("MongoDB connection configuration", function () {
+  const original = {
+    MONGODB_URI: config.MONGODB_URI,
+    DB_USERNAME: config.DB_USERNAME,
+    DB_PASSWORD: config.DB_PASSWORD,
+    DB_HOSTNAME: config.DB_HOSTNAME,
+  };
+
+  afterEach(function () {
+    Object.assign(config, original);
+  });
+
+  it("uses a complete replica-set URI when configured", function () {
+    const uri =
+      "mongodb://user:password@mongo-primary.internal:27017/production" +
+      "?authSource=admin&replicaSet=rs0&w=majority";
+    config.MONGODB_URI = uri;
+
+    expect(getMongoUrl()).to.equal(uri);
+  });
+
+  it("retains the existing single-node connection fallback", function () {
+    config.MONGODB_URI = "";
+    config.DB_USERNAME = "user";
+    config.DB_PASSWORD = "password";
+    config.DB_HOSTNAME = "mongodb";
+
+    expect(getMongoUrl()).to.equal(
+      "mongodb://user:password@mongodb:27017/production"
+    );
+  });
+});