Add in memory version of command bus not handling commands

Author: aliondev

src/Contexts/Shared/domain/Command.ts

@@ -0,0 +1,7 @@
+export abstract class Command {
+  readonly commandName: string;
+
+  constructor(commandName: string) {
+    this.commandName = commandName;
+  }
+}

src/Contexts/Shared/domain/CommandBus.ts

@@ -0,0 +1,5 @@
+import { Command } from './Command';
+
+export interface CommandBus {
+  dispatch(command: Command): void;
+}

src/Contexts/Shared/infrastructure/CommandBus/InMemoryCommandBus.ts

@@ -0,0 +1,9 @@
+import { CommandBus } from './../../domain/CommandBus';
+import { Command } from '../../domain/Command';
+import { NoHandlerForMessageError } from './NoHandlerForMessageError';
+
+export class InMemoryCommandBus implements CommandBus {
+  dispatch(command: Command): void {
+    throw new NoHandlerForMessageError(command);
+  }
+}

src/Contexts/Shared/infrastructure/CommandBus/NoHandlerForMessageError.ts

@@ -0,0 +1,7 @@
+import { Command } from '../../domain/Command';
+
+export class NoHandlerForMessageError extends Error {
+  constructor(command: Command) {
+    super(`There is not handler for command of type ${command.commandName}`);
+  }
+}

tests/Contexts/Shared/infrastructure/CommandBus/InMemoryCommandBus.test.ts

@@ -0,0 +1,24 @@
+import { InMemoryCommandBus } from '../../../../../src/Contexts/Shared/infrastructure/CommandBus/InMemoryCommandBus';
+import { Command } from '../../../../../src/Contexts/Shared/domain/Command';
+import { NoHandlerForMessageError } from '../../../../../src/Contexts/Shared/infrastructure/CommandBus/NoHandlerForMessageError';
+
+class UnhandledCommand extends Command {
+  constructor() {
+    super('UnhandledCommandName');
+  }
+}
+
+describe('InMemoryCommandBus', () => {
+  it('throws an error if dispatches a command without handler', (done) => {
+    const unhandledCommand = new UnhandledCommand();
+    const commandBus = new InMemoryCommandBus();
+
+    try {
+      commandBus.dispatch(unhandledCommand);
+    } catch (error) {
+      expect(error).toBeInstanceOf(NoHandlerForMessageError);
+      expect(error.message).toBe('There is not handler for command of type UnhandledCommandName');
+      done();
+    }
+  });
+});