From ba5ace4ba6baf564a4784813e422e268c9651446 Mon Sep 17 00:00:00 2001
From: Raymond Feng <enjoyjava@gmail.com>
Date: Tue, 7 Aug 2018 10:51:49 -0700
Subject: [PATCH] fix(context): check constructor/method override for @inject

https://github.com/strongloop/loopback-next/issues/1565
---
 packages/context/src/inject.ts            | 14 ++++++++++++++
 packages/context/test/unit/inject.unit.ts | 14 ++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/packages/context/src/inject.ts b/packages/context/src/inject.ts
index 5122504772e7..ed7ecc02374d 100644
--- a/packages/context/src/inject.ts
+++ b/packages/context/src/inject.ts
@@ -10,6 +10,7 @@ import {
   PropertyDecoratorFactory,
   MetadataMap,
   MetadataAccessor,
+  InspectionOptions,
 } from '@loopback/metadata';
 import {BoundValue, ValueOrPromise, resolveList} from './value-promise';
 import {Context} from './context';
@@ -299,10 +300,23 @@ export function describeInjectedArguments(
   method?: string,
 ): Readonly<Injection>[] {
   method = method || '';
+  const options: InspectionOptions = {};
+  if (method === '') {
+    // A hacky way to check if an explicit constructor exists
+    // See https://github.com/strongloop/loopback-next/issues/1565
+    if (target.toString().match(/\s+constructor\s*\([^\)]*\)\s+\{/m)) {
+      options.ownMetadataOnly = true;
+    }
+  } else if (target.hasOwnProperty(method)) {
+    // The method exists in the target, no injections on the super method
+    // should be honored
+    options.ownMetadataOnly = true;
+  }
   const meta = MetadataInspector.getAllParameterMetadata<Readonly<Injection>>(
     PARAMETERS_KEY,
     target,
     method,
+    options,
   );
   return meta || [];
 }
diff --git a/packages/context/test/unit/inject.unit.ts b/packages/context/test/unit/inject.unit.ts
index 2a149a098230..acbd71151afd 100644
--- a/packages/context/test/unit/inject.unit.ts
+++ b/packages/context/test/unit/inject.unit.ts
@@ -79,6 +79,20 @@ describe('function argument injection', () => {
     const meta = describeInjectedArguments(SubTestClass);
     expect(meta.map(m => m.bindingKey)).to.deepEqual(['bar']);
   });
+
+  it('supports inheritance with overriding constructor - no args', () => {
+    class TestClass {
+      constructor(@inject('foo') foo: string) {}
+    }
+
+    class SubTestClass extends TestClass {
+      constructor() {
+        super('foo');
+      }
+    }
+    const meta = describeInjectedArguments(SubTestClass);
+    expect(meta.map(m => m.bindingKey)).to.deepEqual([]);
+  });
 });
 
 describe('property injection', () => {