Add tests for DataloaderInterceptor

Author: dantehemerson

tests/dataloader.interceptor.spec.ts

@@ -0,0 +1,51 @@
+import { CallHandler } from "@nestjs/common";
+import { ModuleRef } from "@nestjs/core";
+import { ExecutionContextHost } from "@nestjs/core/helpers/execution-context-host";
+import { Test } from "@nestjs/testing";
+import { DataLoaderInterceptor } from "../index";
+
+describe(DataLoaderInterceptor.name, () => {
+  let interceptor: DataLoaderInterceptor
+  let handler: CallHandler
+
+  beforeAll(async () => {
+    const testingModule = await Test.createTestingModule({}).compile();
+
+    interceptor = new DataLoaderInterceptor(testingModule.get(ModuleRef))
+
+    handler = {
+      handle: jest.fn()
+    }
+  })
+
+  afterEach(() => {
+    jest.clearAllMocks()
+  })
+
+  it('should be defined', () => {
+    expect(interceptor).toBeDefined()
+  })
+
+  describe('when context is GraphQL', () => {
+    it('should inject dataloader', () => {
+      const gqlExecutionContext = {}
+      const executionContextHost =  new ExecutionContextHost([undefined, undefined, gqlExecutionContext])
+      
+      interceptor.intercept(executionContextHost, handler) 
+  
+      expect(handler.handle).toHaveBeenCalled()
+      // expect(contextIdFactoryMock.create).toHaveBeenCalled()
+      expect(gqlExecutionContext['NEST_LOADER_CONTEXT_KEY']).not.toBeUndefined()
+    })
+  })
+
+  describe('when context is not GraphQL', () => {
+    it('should not inject dataloader', () => {
+      const executionContextHost =  new ExecutionContextHost([])
+      
+      interceptor.intercept(executionContextHost, handler) 
+  
+      expect(handler.handle).toHaveBeenCalled()
+    })
+  })
+})