refactor(MQTT Node): Refactor, fix duplicate triggers, and add Unit tests (#9847)

Co-authored-by: Elias Meire <elias@meire.dev>

packages/nodes-base/nodes/MQTT/test/Mqtt.node.test.ts

@@ -0,0 +1,56 @@
+import type { MqttClient } from 'mqtt';
+import { mock } from 'jest-mock-extended';
+import type { ICredentialDataDecryptedObject, IExecuteFunctions } from 'n8n-workflow';
+
+import { Mqtt } from '../Mqtt.node';
+import { createClient } from '../GenericFunctions';
+
+jest.mock('../GenericFunctions', () => {
+	const mockMqttClient = mock<MqttClient>();
+	return {
+		createClient: jest.fn().mockResolvedValue(mockMqttClient),
+	};
+});
+
+describe('MQTT Node', () => {
+	const credentials = mock<ICredentialDataDecryptedObject>();
+	const executeFunctions = mock<IExecuteFunctions>();
+
+	beforeEach(() => {
+		jest.clearAllMocks();
+
+		executeFunctions.getCredentials.calledWith('mqtt').mockResolvedValue(credentials);
+		executeFunctions.getInputData.mockReturnValue([{ json: { testing: true } }]);
+		executeFunctions.getNodeParameter.calledWith('topic', 0).mockReturnValue('test/topic');
+		executeFunctions.getNodeParameter.calledWith('options', 0).mockReturnValue({});
+	});
+
+	it('should publish input data', async () => {
+		executeFunctions.getNodeParameter.calledWith('sendInputData', 0).mockReturnValue(true);
+
+		const result = await new Mqtt().execute.call(executeFunctions);
+
+		expect(result).toEqual([[{ json: { testing: true } }]]);
+		expect(executeFunctions.getCredentials).toHaveBeenCalledTimes(1);
+		expect(executeFunctions.getNodeParameter).toHaveBeenCalledTimes(3);
+
+		const mockMqttClient = await createClient(mock());
+		expect(mockMqttClient.publishAsync).toHaveBeenCalledWith('test/topic', '{"testing":true}', {});
+		expect(mockMqttClient.endAsync).toHaveBeenCalledTimes(1);
+	});
+
+	it('should publish a custom message', async () => {
+		executeFunctions.getNodeParameter.calledWith('sendInputData', 0).mockReturnValue(false);
+		executeFunctions.getNodeParameter.calledWith('message', 0).mockReturnValue('Hello, MQTT!');
+
+		const result = await new Mqtt().execute.call(executeFunctions);
+
+		expect(result).toEqual([[{ json: { testing: true } }]]);
+		expect(executeFunctions.getCredentials).toHaveBeenCalledTimes(1);
+		expect(executeFunctions.getNodeParameter).toHaveBeenCalledTimes(4);
+
+		const mockMqttClient = await createClient(mock());
+		expect(mockMqttClient.publishAsync).toHaveBeenCalledWith('test/topic', 'Hello, MQTT!', {});
+		expect(mockMqttClient.endAsync).toHaveBeenCalledTimes(1);
+	});
+});