From f6ae117a949c353267ccd21bb7b5239705c6a62e Mon Sep 17 00:00:00 2001
From: Iku-turso <mikko.aspiala@gmail.com>
Date: Tue, 22 Nov 2022 13:55:18 +0200
Subject: [PATCH] feat: Permit override of single injectable using injection
 token

---
 .../createContainer.js                        | 22 ++++-
 .../createContainer.override.test.js          | 86 +++++++++++++++++++
 2 files changed, 106 insertions(+), 2 deletions(-)

diff --git a/packages/injectable/core/src/dependency-injection-container/createContainer.js b/packages/injectable/core/src/dependency-injection-container/createContainer.js
index 116a01a9..5abafe86 100644
--- a/packages/injectable/core/src/dependency-injection-container/createContainer.js
+++ b/packages/injectable/core/src/dependency-injection-container/createContainer.js
@@ -238,9 +238,25 @@ export default containerId => {
     },
 
     override: (alias, instantiateStub) => {
-      const originalInjectable = injectableMap.get(alias.id);
+      const relatedInjectables = getRelatedInjectables(alias);
+
+      if (relatedInjectables.length > 1) {
+        throw new Error(
+          `Tried to override single implementation of injection token "${
+            alias.id
+          }", but found multiple registered implementations: "${relatedInjectables
+            .map(x => x.id)
+            .join('", "')}".`,
+        );
+      }
+
+      if (relatedInjectables.length === 0) {
+        if (alias.aliasType === 'injection-token') {
+          throw new Error(
+            `Tried to override single implementation of injection token "${alias.id}", but found no registered implementations.`,
+          );
+        }
 
-      if (!originalInjectable) {
         throw new Error(
           `Tried to override "${alias.id}" which is not registered.`,
         );
@@ -252,6 +268,8 @@ export default containerId => {
         );
       }
 
+      const originalInjectable = relatedInjectables[0];
+
       overridingInjectables.set(originalInjectable.id, {
         ...originalInjectable,
         causesSideEffects: false,
diff --git a/packages/injectable/core/src/dependency-injection-container/createContainer.override.test.js b/packages/injectable/core/src/dependency-injection-container/createContainer.override.test.js
index ff0bb385..47c1f35e 100644
--- a/packages/injectable/core/src/dependency-injection-container/createContainer.override.test.js
+++ b/packages/injectable/core/src/dependency-injection-container/createContainer.override.test.js
@@ -203,4 +203,90 @@ describe('createContainer.override', () => {
 
     expect(actual).toEqual(['some-override']);
   });
+
+  it('given single registered injectable with injection token, and the injection token is overridden, when the injection token is inject-singled, injects the overridden instance', () => {
+    const di = createContainer('some-container');
+
+    const someInjectionToken = getInjectionToken({
+      id: 'some-injection-token',
+    });
+
+    const injectable = getInjectable({
+      id: 'some-injectable',
+      instantiate: () => 'irrelevant',
+      injectionToken: someInjectionToken,
+    });
+
+    di.register(injectable);
+
+    di.override(someInjectionToken, () => 'some-override');
+
+    const actual = di.inject(someInjectionToken);
+
+    expect(actual).toBe('some-override');
+  });
+
+  it('given single registered injectable with injection token, and the injection token is overridden, when the injection token is inject-many, injects the overridden instance', () => {
+    const di = createContainer('some-container');
+
+    const someInjectionToken = getInjectionToken({
+      id: 'some-injection-token',
+    });
+
+    const injectable = getInjectable({
+      id: 'some-injectable',
+      instantiate: () => 'irrelevant',
+      injectionToken: someInjectionToken,
+    });
+
+    di.register(injectable);
+
+    di.override(someInjectionToken, () => 'some-override');
+
+    const actual = di.injectMany(someInjectionToken);
+
+    expect(actual).toEqual(['some-override']);
+  });
+
+  it('given multiple registered injectables with injection token, and the injection token is overridden, throws', () => {
+    const di = createContainer('some-container');
+
+    const someInjectionToken = getInjectionToken({
+      id: 'some-injection-token',
+    });
+
+    const injectable1 = getInjectable({
+      id: 'some-injectable-1',
+      instantiate: () => 'irrelevant',
+      injectionToken: someInjectionToken,
+    });
+
+    const injectable2 = getInjectable({
+      id: 'some-injectable-2',
+      instantiate: () => 'irrelevant',
+      injectionToken: someInjectionToken,
+    });
+
+    di.register(injectable1, injectable2);
+
+    expect(() => {
+      di.override(someInjectionToken, () => 'some-override');
+    }).toThrow(
+      'Tried to override single implementation of injection token "some-injection-token", but found multiple registered implementations: "some-injectable-1", "some-injectable-2".',
+    );
+  });
+
+  it('given no registered injectable with injection token, when the injection token is overridden, throws', () => {
+    const di = createContainer('some-container');
+
+    const someInjectionToken = getInjectionToken({
+      id: 'some-injection-token',
+    });
+
+    expect(() => {
+      di.override(someInjectionToken, () => 'some-override');
+    }).toThrow(
+      'Tried to override single implementation of injection token "some-injection-token", but found no registered implementations.',
+    );
+  });
 });