test: improve coverage for init database

### Description\nImplement unit tests for init database feature using nock.\n\n### Scenarios Tested\n- Defaults without project ID\n- Downloading rules with project ID\n- Actuate writing rules

Author: joehan

src/init/features/database.spec.ts

@@ -0,0 +1,132 @@
+import { expect } from "chai";
+import * as sinon from "sinon";
+import * as nock from "nock";
+import { askQuestions, actuate, DEFAULT_RULES } from "./database";
+import * as prompt from "../../prompt";
+import * as getDefaultDatabaseInstanceModule from "../../getDefaultDatabaseInstance";
+import * as databaseManagement from "../../management/database";
+import * as ensureApiEnabled from "../../ensureApiEnabled";
+import { Config } from "../../config";
+import { FirebaseError } from "../../error";
+
+describe("init/features/database", () => {
+  let confirmStub: sinon.SinonStub;
+  let inputStub: sinon.SinonStub;
+  let selectStub: sinon.SinonStub;
+  let getDefaultInstanceStub: sinon.SinonStub;
+  let getDatabaseInstanceDetailsStub: sinon.SinonStub;
+  let ensureStub: sinon.SinonStub;
+  let configWriteStub: sinon.SinonStub;
+  let configConfirmWriteStub: sinon.SinonStub;
+
+  beforeEach(() => {
+    confirmStub = sinon.stub(prompt, "confirm");
+    inputStub = sinon.stub(prompt, "input");
+    selectStub = sinon.stub(prompt, "select");
+    getDefaultInstanceStub = sinon.stub(getDefaultDatabaseInstanceModule, "getDefaultDatabaseInstance");
+    getDatabaseInstanceDetailsStub = sinon.stub(databaseManagement, "getDatabaseInstanceDetails");
+    ensureStub = sinon.stub(ensureApiEnabled, "ensure").resolves();
+    configWriteStub = sinon.stub(Config.prototype, "writeProjectFile");
+    configConfirmWriteStub = sinon.stub(Config.prototype, "confirmWriteProjectFile");
+  });
+
+  afterEach(() => {
+    sinon.restore();
+    nock.cleanAll();
+  });
+
+  describe("askQuestions", () => {
+    it("should setup defaults when no project ID is present", async () => {
+      inputStub.resolves("database.rules.json");
+      configConfirmWriteStub.resolves(true);
+      const setup: any = { config: {} };
+      const config = new Config({}, {});
+
+      await askQuestions(setup, config);
+
+      expect(setup.featureInfo.database.rulesFilename).to.equal("database.rules.json");
+      expect(setup.featureInfo.database.rules).to.equal(DEFAULT_RULES);
+    });
+
+    it("should download rules from existing instance if project ID is present", async () => {
+      inputStub.resolves("database.rules.json");
+      configConfirmWriteStub.resolves(true);
+      getDefaultInstanceStub.resolves("my-instance");
+      getDatabaseInstanceDetailsStub.resolves({
+        name: "my-instance",
+        databaseUrl: "https://my-instance.firebaseio.com",
+      });
+
+      const mockRules = '{ "rules": { ".read": true } }';
+      nock("https://my-instance.firebaseio.com")
+        .get("/.settings/rules.json")
+        .reply(200, mockRules);
+
+      const setup: any = { projectId: "my-project", config: {} };
+      const config = new Config({}, {});
+
+      await askQuestions(setup, config);
+
+      expect(setup.featureInfo.database.rules).to.equal(mockRules);
+    });
+
+    it("should throw if rules fetch fails", async () => {
+      inputStub.resolves("database.rules.json");
+      getDefaultInstanceStub.resolves("my-instance");
+      getDatabaseInstanceDetailsStub.resolves({
+        name: "my-instance",
+        databaseUrl: "https://my-instance.firebaseio.com",
+      });
+
+      nock("https://my-instance.firebaseio.com")
+        .get("/.settings/rules.json")
+        .reply(500);
+
+      const setup: any = { projectId: "my-project", config: {} };
+      const config = new Config({}, {});
+
+      await expect(askQuestions(setup, config)).to.be.rejectedWith(
+        FirebaseError,
+        /Failed to fetch current rules/
+      );
+    });
+  });
+
+  describe("actuate", () => {
+    it("should write rules to file if writeRules is true", async () => {
+      const setup: any = {
+        config: {},
+        featureInfo: {
+          database: {
+            rulesFilename: "database.rules.json",
+            rules: DEFAULT_RULES,
+            writeRules: true,
+          },
+        },
+      };
+      const config = new Config({}, {});
+
+      await actuate(setup, config);
+
+      expect(configWriteStub).to.have.been.calledWith("database.rules.json", DEFAULT_RULES);
+    });
+
+    it("should skip writing rules if writeRules is false", async () => {
+      const setup: any = {
+        config: {},
+        featureInfo: {
+          database: {
+            rulesFilename: "database.rules.json",
+            rules: DEFAULT_RULES,
+            writeRules: false,
+          },
+        },
+      };
+      const config = new Config({}, {});
+
+      await actuate(setup, config);
+
+      expect(configWriteStub).to.not.have.been.called;
+    });
+  });
+});