feat(command-bus): introduce typed context to local command bus

package.json

@@ -26,5 +26,6 @@
     "lint-staged": {
         "*.ts": "eslint --fix",
         "*.json": "prettier --write"
-    }
+    },
+    "packageManager": "pnpm@9.9.0+sha512.60c18acd138bff695d339be6ad13f7e936eea6745660d4cc4a776d5247c540d0edee1a563695c183a66eb917ef88f2b4feb1fc25f32a7adcadc7aaf3438e99c1"
 }

packages/ddd-toolkit/src/command-bus/command-bus.interface.ts

@@ -8,12 +8,15 @@ export interface ICommandClass<C extends ICommand<unknown, unknown>> {
     new (payload: unknown): C;
 }
 
-export interface ICommandHandler<C extends ICommand<unknown, unknown>> {
-    handle: (command: C) => Promise<C['_returnType']>;
+export interface ICommandHandler<C extends ICommand<unknown, unknown>, TContext = void> {
+    handle: (command: C, context?: TContext) => Promise<C['_returnType']>;
 }
 
-export interface ICommandBus {
-    register<C extends ICommand<unknown, unknown>>(command: ICommandClass<C>, handler: ICommandHandler<C>): void;
+export interface ICommandBus<TContext> {
+    register<C extends ICommand<unknown, unknown>>(
+        command: ICommandClass<C>,
+        handler: ICommandHandler<C, TContext>,
+    ): void;
 
     send<C extends ICommand<unknown, unknown>>(command: C): Promise<void>;
 }

packages/ddd-toolkit/src/command-bus/context-manager.interface.ts

@@ -0,0 +1,3 @@
+export interface IContextManager<TContext> {
+    wrapWithContext<T>(operation: (context: TContext) => Promise<T>): Promise<T>;
+}

packages/ddd-toolkit/src/command-bus/local-command-bus.spec.ts

@@ -3,6 +3,7 @@ import { Command } from './command';
 import { waitFor } from '../utils';
 import { ICommandHandler } from './command-bus.interface';
 import { ILogger } from '../logger';
+import { IContextManager } from './context-manager.interface';
 
 const loggerMock: ILogger = {
     log: jest.fn(),
@@ -24,17 +25,15 @@ class BarCommand extends Command<{ foo: string }> {
 }
 
 describe('LocalCommandBus', () => {
+    afterEach(() => jest.resetAllMocks());
+
     describe('Given an command bus', () => {
-        let commandBus: LocalCommandBus;
+        let commandBus: LocalCommandBus<unknown>;
 
         beforeEach(() => {
             commandBus = new LocalCommandBus(loggerMock, 3, 100);
         });
 
-        afterEach(() => {
-            jest.resetAllMocks();
-        });
-
         describe('Given no registered handler to foo command', () => {
             describe('When send a foo command', () => {
                 it('Should log warning message', async () => {
@@ -160,6 +159,50 @@ describe('LocalCommandBus', () => {
         });
     });
 
+    describe('Given a command bus with context manager', () => {
+        type TContext = { contextKey: string };
+
+        let commandBus: LocalCommandBus<TContext>;
+
+        class FooContextManager implements IContextManager<TContext> {
+            public async wrapWithContext<T>(operation: (context: TContext) => Promise<T>): Promise<T> {
+                const context: TContext = { contextKey: 'foo-bar' };
+                return await operation(context);
+            }
+        }
+
+        beforeEach(() => {
+            commandBus = new LocalCommandBus(loggerMock, 3, 100, new FooContextManager());
+        });
+
+        it('should be defined', () => {
+            expect(commandBus).toBeDefined();
+        });
+
+        describe('Given one registered handler to foo command', () => {
+            const FooHandlerMock = jest.fn();
+
+            class FooCommandHandler implements ICommandHandler<FooCommand> {
+                async handle(...args: unknown[]) {
+                    return await FooHandlerMock(args);
+                }
+            }
+
+            beforeEach(() => {
+                commandBus.register(FooCommand, new FooCommandHandler());
+            });
+
+            describe('When sendSync a foo command', () => {
+                it('context should be passed to command', async () => {
+                    const command = new FooCommand({ foo: 'bar' });
+                    await commandBus.sendSync(command);
+
+                    expect(FooHandlerMock).toHaveBeenCalledWith([command, { contextKey: 'foo-bar' }]);
+                });
+            });
+        });
+    });
+
     it('default retry max attempts should be 0', () => {
         const commandBus = new LocalCommandBus(loggerMock);
         expect(commandBus['retryMaxAttempts']).toBe(0);

packages/ddd-toolkit/src/command-bus/local-command-bus.ts

@@ -2,30 +2,32 @@ import { ILogger } from '../logger';
 import { ICommand, ICommandBus, ICommandClass, ICommandHandler } from './command-bus.interface';
 import { ExponentialBackoff, IRetryMechanism } from '../event-bus';
 import { inspect } from 'util';
+import { IContextManager } from './context-manager.interface';
 
-export class LocalCommandBus implements ICommandBus {
+export class LocalCommandBus<TContext = void> implements ICommandBus<TContext> {
     private readonly retryMechanism: IRetryMechanism;
 
-    private handlers: { [key: string]: ICommandHandler<ICommand<unknown, unknown>> } = {};
+    private handlers: { [key: string]: ICommandHandler<ICommand<unknown, unknown>, TContext> } = {};
 
     constructor(
         private logger: ILogger,
         private readonly retryMaxAttempts = 0,
         retryInitialDelay = 500,
+        private readonly contextManager?: IContextManager<TContext>,
     ) {
         this.retryMechanism = new ExponentialBackoff(retryInitialDelay);
     }
 
     public register<C extends ICommand<unknown, unknown>>(
         command: ICommandClass<C>,
-        handler: ICommandHandler<C>,
+        handler: ICommandHandler<C, TContext>,
     ): void {
         if (this.handlers[command.name]) throw new Error(`Command ${command.name} is already registered`);
         this.handlers[command.name] = handler;
     }
 
     public async send<C extends ICommand<unknown, unknown>>(command: C): Promise<void> {
-        const handler = this.handlers[command.name] as ICommandHandler<C>;
+        const handler = this.handlers[command.name] as ICommandHandler<C, TContext>;
         if (!handler) {
             this.logger.warn(`No handler found for ${command.name}`);
             return;
@@ -35,14 +37,19 @@ export class LocalCommandBus implements ICommandBus {
     }
 
     public async sendSync<C extends ICommand<unknown, unknown>>(command: C): Promise<C['_returnType']> {
-        const handler = this.handlers[command.name] as ICommandHandler<C>;
+        const handler = this.handlers[command.name] as ICommandHandler<C, TContext>;
         if (!handler) throw new Error(`No handler found for ${command.name}`);
-        return await handler.handle(command);
+
+        return this.contextManager
+            ? await this.contextManager.wrapWithContext(async (context) => {
+                  return await handler.handle(command, context);
+              })
+            : await handler.handle(command);
     }
 
     private async handleCommand<C extends ICommand<unknown, unknown>>(
         command: C,
-        handler: ICommandHandler<C>,
+        handler: ICommandHandler<C, TContext>,
         attempt = 0,
     ) {
         try {