non-array params coerced into array

src/JsonRpc.test.ts

@@ -3,76 +3,68 @@ import JsonRpc, {ErrorCodes} from './JsonRpc';
 const defer = (ms: number, val?: any) =>
   new Promise(resolve => setTimeout(() => resolve(val), ms));
 
-it('handles requests', async () => {
-  const rpc = new JsonRpc({
-    methods: {
-      hello: () => 'goodbye',
-    },
-  });
-
-  const request = {
-    id: 123,
-    jsonrpc: '2.0',
-    method: 'hello',
-  };
-
-  const response = await (rpc as any).handleRequest(request);
-  expect(response).toEqual({
+describe('handling requests', () => {
+  let rpc: any;
+  const buildRequest = (method: string, params?: any[] | object) => ({
     jsonrpc: '2.0',
     id: 123,
-    result: 'goodbye',
+    method,
+    params,
   });
-});
 
-it('waits on promise results', async () => {
-  const rpc = new JsonRpc({
-    methods: {
-      deferred: () => Promise.resolve('deferredResult'),
-    },
+  beforeEach(() => {
+    rpc = new JsonRpc({
+      methods: {
+        hello: (name: string) => `goodbye ${name}`,
+        canVote: (voter: {age: number}) => voter.age > 18,
+        deferred: () => Promise.resolve('deferredResult'),
+        blowUp: () => {
+          throw Error('BOOM!');
+        },
+      },
+    });
   });
 
-  const request = {
-    id: 123,
-    jsonrpc: '2.0',
-    method: 'deferred',
-  };
+  it('handles array params', async () => {
+    const request = buildRequest('hello', ['Alice']);
+    const response = await rpc.handleRequest(request);
 
-  const response = await (rpc as any).handleRequest(request);
-  expect(response.result).toEqual('deferredResult');
-});
+    expect(response.jsonrpc).toEqual('2.0');
+    expect(response.id).toEqual(request.id);
+    expect(response.result).toEqual('goodbye Alice');
+  });
 
-it('errors on missing method', async () => {
-  const rpc = new JsonRpc();
+  it('handles object params', async () => {
+    const request = buildRequest('canVote', {age: 22});
+    const response = await rpc.handleRequest(request);
 
-  const request = {
-    id: 123,
-    jsonrpc: '2.0',
-    method: 'missing',
-  };
+    expect(response.jsonrpc).toEqual('2.0');
+    expect(response.id).toEqual(request.id);
+    expect(response.result).toEqual(true);
+  });
 
-  const response = await (rpc as any).handleRequest(request);
-  expect(response.id).toEqual(123);
-  expect(response.error.code).toEqual(ErrorCodes.MethodNotFound);
-});
+  it('waits on promise results', async () => {
+    const request = buildRequest('deferred');
+    const response = await rpc.handleRequest(request);
 
-it('errors on throwing method', async () => {
-  const rpc = new JsonRpc({
-    methods: {
-      blowUp: () => {
-        throw Error('BOOM!');
-      },
-    },
+    expect(response.result).toEqual('deferredResult');
   });
 
-  const request = {
-    id: 123,
-    jsonrpc: '2.0',
-    method: 'blowUp',
-  };
+  it('errors on missing method', async () => {
+    const request = buildRequest('missing');
+    const response = await rpc.handleRequest(request);
 
-  const response = await (rpc as any).handleRequest(request);
-  expect(response.id).toEqual(123);
-  expect(response.error.code).toEqual(ErrorCodes.InternalError);
+    expect(response.id).toEqual(request.id);
+    expect(response.error.code).toEqual(ErrorCodes.MethodNotFound);
+  });
+
+  it('errors on throwing method', async () => {
+    const request = buildRequest('blowUp');
+    const response = await rpc.handleRequest(request);
+
+    expect(response.id).toEqual(request.id);
+    expect(response.error.code).toEqual(ErrorCodes.InternalError);
+  });
 });
 
 describe('mounted', () => {

src/JsonRpc.ts

@@ -59,6 +59,9 @@ const buildErrorResponse = (id: number) => (error: {
   },
 });
 
+const ensureArray = (source: any) =>
+  Array.isArray(source) ? source : [source];
+
 class JsonRpc {
   private methods: Methods;
   private destination: JsonRpcDestination;
@@ -91,12 +94,21 @@ class JsonRpc {
     return promise;
   }
 
+  mount(source: EventTarget) {
+    this.source = source;
+    source.addEventListener('message', this.handleMessage);
+  }
+
+  unmount() {
+    this.source.removeEventListener('message', this.handleMessage);
+  }
+
   private handleRequest(request: JsonRpcRequest): Promise<JsonRpcResponse> {
     return Promise.resolve()
       .then(() => {
         const method = this.methods[request.method];
         return method
-          ? method.apply(null, request.params)
+          ? method.apply(null, ensureArray(request.params))
           : Promise.reject({
               code: ErrorCodes.MethodNotFound,
               message: 'Method not found',
@@ -132,15 +144,6 @@ class JsonRpc {
       this.handleResponse(e.data);
     }
   };
-
-  mount(source: EventTarget) {
-    this.source = source;
-    source.addEventListener('message', this.handleMessage);
-  }
-
-  unmount() {
-    this.source.removeEventListener('message', this.handleMessage);
-  }
 }
 
 export default JsonRpc;