fix(context): calculate # of method params with default

Fixes #1408

packages/context/src/resolver.ts

@@ -157,13 +157,16 @@ export function resolveInjectedArguments(
   const extraArgs = nonInjectedArgs || [];
 
   let argLength = DecoratorFactory.getNumberOfParameters(target, method);
-  if (argLength < injectedArgs.length) {
+
+  // Please note `injectedArgs` contains `undefined` for non-injected args
+  const numberOfInjected = injectedArgs.filter(i => i != null).length;
+  if (argLength < numberOfInjected + extraArgs.length) {
     /**
      * `Function.prototype.length` excludes the rest parameter and only includes
      * parameters before the first one with a default value. For example,
-     * `hello(@inject('name') name: string)` gives 0 for argLength
+     * `hello(@inject('name') name: string = 'John')` gives 0 for argLength
      */
-    argLength = injectedArgs.length;
+    argLength = numberOfInjected + extraArgs.length;
   }
 
   let nonInjectedIndex = 0;

packages/context/test/acceptance/method-level-bindings.acceptance.ts

@@ -29,6 +29,15 @@ class InfoController {
     debug(msg);
     return msg;
   }
+
+  greetWithDefault(
+    prefix: string = '***',
+    @inject('user') user: string,
+  ): string {
+    const msg = `[${prefix}] Hello ${user}`;
+    debug(msg);
+    return msg;
+  }
 }
 
 const INFO_CONTROLLER = 'controllers.info';
@@ -60,6 +69,13 @@ describe('Context bindings - Injecting dependencies of method', () => {
     expect(msg).to.eql('[INFO] Hello John');
   });
 
+  it('injects prototype method args with non-injected ones with default', async () => {
+    const instance = await ctx.get(INFO_CONTROLLER);
+    // Invoke the `hello` method => Hello John
+    const msg = await invokeMethod(instance, 'greetWithDefault', ctx, ['INFO']);
+    expect(msg).to.eql('[INFO] Hello John');
+  });
+
   it('injects static method args', async () => {
     // Invoke the `sayHello` method => Hello John
     const msg = await invokeMethod(InfoController, 'sayHello', ctx);