docker-utils: Test network gateway determination logic

Change-type: patch
Signed-off-by: Rich Bayliss <rich@balena.io>

test/31-docker-utils.spec.ts

@@ -0,0 +1,56 @@
+import { expect } from 'chai';
+import { testWithData } from './lib/mocked-dockerode';
+
+import * as dockerUtils from '../src/lib/docker-utils';
+
+describe('Docker Utils', () => {
+	describe('Supervisor Address', () => {
+		// setup some fake data...
+		const networks = {
+			supervisor0: {
+				IPAM: {
+					Config: [
+						{
+							Gateway: '10.0.105.1',
+							Subnet: '10.0.105.0/16',
+						},
+					],
+				},
+			},
+		};
+
+		// test using existing data...
+		it('should return the correct gateway address for supervisor0', async () => {
+			await testWithData({ networks }, async () => {
+				const gateway = await dockerUtils.getNetworkGateway('supervisor0');
+				expect(gateway).to.equal('10.0.105.1');
+			});
+		});
+
+		it('should return the correct gateway address for host', async () => {
+			await testWithData({ networks }, async () => {
+				const gateway = await dockerUtils.getNetworkGateway('host');
+				expect(gateway).to.equal('127.0.0.1');
+			});
+		});
+	});
+
+	describe('Image Environment', () => {
+		const images = {
+			['test-image']: {
+				Config: {
+					Env: ['TEST_VAR_1=1234', 'TEST_VAR_2=5678'],
+				},
+			},
+		};
+
+		// test using existing data...
+		it('should return the correct image environment', async () => {
+			await testWithData({ images }, async () => {
+				const obj = await dockerUtils.getImageEnv('test-image');
+				expect(obj).to.have.property('TEST_VAR_1').equal('1234');
+				expect(obj).to.have.property('TEST_VAR_2').equal('5678');
+			});
+		});
+	});
+});

test/lib/mocked-dockerode.ts

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+import * as dockerode from 'dockerode';
+
+export interface TestData {
+	networks: Dictionary<any>;
+	images: Dictionary<any>;
+}
+
+function createMockedDockerode(data: TestData) {
+	const mockedDockerode = dockerode.prototype;
+	mockedDockerode.getNetwork = (id: string) => {
+		return {
+			inspect: async () => {
+				return data.networks[id];
+			},
+		} as dockerode.Network;
+	};
+
+	mockedDockerode.getImage = (name: string) => {
+		return {
+			inspect: async () => {
+				return data.images[name];
+			},
+		} as dockerode.Image;
+	};
+
+	return mockedDockerode;
+}
+
+export async function testWithData(
+	data: Partial<TestData>,
+	test: () => Promise<any>,
+) {
+	const mockedData: TestData = {
+		...{
+			networks: {},
+			images: {},
+			containers: {},
+		},
+		...data,
+	};
+
+	// grab the original prototype...
+	const basePrototype = dockerode.prototype;
+
+	// @ts-expect-error setting a RO property
+	dockerode.prototype = createMockedDockerode(mockedData);
+
+	try {
+		// run the test...
+		await test();
+	} finally {
+		// reset the original prototype...
+		// @ts-expect-error setting a RO property
+		dockerode.prototype = basePrototype;
+	}
+}