feat(core): add falsy values handling

ensure isValueProvider returns true for falsy values

Author: thiagomini

packages/core/injector/helpers/provider-classifier.ts

@@ -4,13 +4,15 @@ import {
   Provider,
   ValueProvider,
 } from '@nestjs/common';
+import { isUndefined } from '@nestjs/common/utils/shared.utils';
 
 export function isClassProvider(provider: Provider): boolean {
   return Boolean((provider as ClassProvider)?.useClass);
 }
 
 export function isValueProvider(provider: Provider): boolean {
-  return Boolean((provider as ValueProvider)?.useValue);
+  const providerValue = (provider as ValueProvider)?.useValue;
+  return !isUndefined(providerValue);
 }
 
 export function isFactoryProvider(provider: Provider): boolean {

packages/core/test/injector/helpers/provider-classifier.spec.ts

@@ -51,6 +51,33 @@ describe('provider classifier', () => {
       expect(isValueProvider(valueProvider)).to.be.true;
     });
 
+    it('should return true if useValue is "false"', () => {
+      const valueProvider: ValueProvider = {
+        useValue: false,
+        provide: 'token',
+      };
+
+      expect(isValueProvider(valueProvider)).to.be.true;
+    });
+
+    it('should return true if useValue is "null"', () => {
+      const valueProvider: ValueProvider = {
+        useValue: null,
+        provide: 'token',
+      };
+
+      expect(isValueProvider(valueProvider)).to.be.true;
+    });
+
+    it('should return true if useValue is an empty string', () => {
+      const valueProvider: ValueProvider = {
+        useValue: null,
+        provide: '',
+      };
+
+      expect(isValueProvider(valueProvider)).to.be.true;
+    });
+
     it('should return false if useValue is undefined', () => {
       const valueProvider: ValueProvider = {
         useValue: undefined,