Add tests for isServiceProvider() util

tests/browser/packages/support/services/isServiceProvider.test.js

@@ -0,0 +1,44 @@
+import { isServiceProvider, ServiceProvider } from "@aedart/support/services";
+
+describe('@aedart/support/services', () => {
+    describe('isServiceProvider()', () => {
+
+        it('can determine if target is a service provider instance', () => {
+
+            class A {}
+
+            class B {
+                register() {}
+
+                boot() {}
+            }
+
+            class C extends B {}
+
+            class D extends ServiceProvider {}
+
+            class E extends D {}
+
+            // ------------------------------------------------------------------------------------ //
+
+            const data = [
+                { value: null, expected: false, name: 'Null' },
+                { value: [], expected: false, name: 'Array' },
+                { value: {}, expected: false, name: 'Object (empty)' },
+                { value: new A(), expected: false, name: 'Class A (empty)' },
+
+                { value: new B(), expected: true, name: 'Class B (custom implementation of service provider)' },
+                { value: new C(), expected: true, name: 'Class C (inherits from custom implementation)' },
+                { value: new D(null), expected: true, name: 'Class D (inherits from ServiceProvider abstraction)' },
+                { value: new E(null), expected: true, name: 'Class E (inherits from a base that inherits from ServiceProvider abstraction)' },
+            ];
+
+            for (const entry of data) {
+                expect(isServiceProvider(entry.value))
+                    .withContext(`${entry.name} was expected to ${entry.expected.toString()}`)
+                    .toBe(entry.expected);
+            }
+        });
+
+    });
+});