Merge pull request #4 from TheBrainFamily/testingServicesInIsolation

feat: Testing services in isolation

README.md

@@ -1,6 +1,8 @@
 # federation-testing-tool
 Test your Apollo GraphQL Gateway / Federation micro services. With this package you don't have to worry about the whole complexity that comes with joining the GraphQL federated micro services and preparing them for testing. 
 
+### NOTE: THIS IS NOT READY YET. I'M OPEN FOR FEEDBACK, BUT PLEASE BE AWARE THAT THE API KEEPS CHANGING EVERYDAY. I DIDN'T EXPECT PEOPLE TO START USING IT! I PLAN TO RELEASE A TUTORIAL THIS COMING WEEKEND AND BY THAT TIME THE PACKAGE WILL BE READY. STAY TUNED.
+
 Install it with 
 ```bash 
 npm install --save-dev federation-testing-tool

index.js

@@ -6,8 +6,13 @@ const {
 } = require("@apollo/gateway");
 const { addMockFunctionsToSchema } = require("graphql-tools");
 const { addResolversToSchema } = require("apollo-graphql");
-
-const { buildFederatedSchema, composeServices } = require("@apollo/federation");
+const { print } = require("graphql");
+const {
+  buildFederatedSchema,
+  composeAndValidate
+} = require("@apollo/federation");
+const clone = require("clone");
+const gql = require("graphql-tag");
 
 function buildLocalService(modules) {
   const schema = buildFederatedSchema(modules);
@@ -24,7 +29,70 @@ function buildRequestContext(variables, context) {
   };
 }
 
-const setupSchema = services => {
+function prepareProviderService(service) {
+  let allTypeNames = [];
+
+  const typeDefsForMockedService = clone(service.typeDefs);
+
+  typeDefsForMockedService.definitions = typeDefsForMockedService.definitions
+    .filter(d => d.name.value !== "Query" && d.name.value !== "Mutation")
+    .filter(d => d.kind === "ObjectTypeExtension");
+
+  typeDefsForMockedService.definitions.forEach(def => {
+    def.kind = "ObjectTypeDefinition";
+    allTypeNames.push(def.name.value);
+
+    def.fields = def.fields.filter(f =>
+      f.directives.find(d => d.name.value === "external")
+    );
+    def.fields.forEach(f => {
+      f.directives = f.directives.filter(d => d.name.value !== "external");
+    });
+  });
+
+  if (allTypeNames.length) {
+    const typesQueries = allTypeNames.map(n => `_get${n}: ${n}`).join("\n");
+    const newTypeDefString = `
+        extend type Query {
+          ${typesQueries}
+        }
+        ${print(typeDefsForMockedService)}
+      `;
+
+    // I'm doing it like this because otherwise IDE screams at me for an incorrect GraphQL string
+    let newTypeDefs = gql`
+      ${newTypeDefString}
+    `;
+
+    return {
+      __provider: {
+        typeDefs: newTypeDefs
+      }
+    };
+  }
+  return undefined;
+}
+
+const setupSchema = serviceOrServices => {
+  let services;
+  if (!serviceOrServices.length) {
+    services = [
+      {
+        serviceUnderTest: {
+          resolvers: serviceOrServices.resolvers,
+          typeDefs: serviceOrServices.typeDefs,
+          underTest: true
+        }
+      }
+    ];
+    const providerService = prepareProviderService(serviceOrServices);
+    if (providerService) {
+      services.push(providerService);
+    }
+  } else {
+    services = serviceOrServices;
+  }
+
   let serviceMap = {};
   services.forEach(service => {
     let serviceName = Object.keys(service)[0];
@@ -39,7 +107,7 @@ const setupSchema = services => {
     })
   );
 
-  let composed = composeServices(mapForComposeServices);
+  let composed = composeAndValidate(mapForComposeServices);
 
   if (composed.errors && composed.errors.length > 0) {
     throw new Error(JSON.stringify(composed.errors));
@@ -80,19 +148,15 @@ function execute(schema, query, mutation, serviceMap, variables, context) {
   );
 }
 
-const executeGraphql = ({
-  query,
-  mutation,
-  variables,
-  context,
+function validateArguments(
   services,
-  mocks = {},
+  service,
   schema,
-  serviceMap
-}) => {
-  if (services) {
-    ({ schema, serviceMap } = setupSchema(services));
-  } else {
+  serviceMap,
+  query,
+  mutation
+) {
+  if (!(services || service)) {
     if (!schema) {
       throw new Error(
         "You need to pass either services array to prepare your schema, or the schema itself, generated by the setupSchema function"
@@ -104,6 +168,27 @@ const executeGraphql = ({
       );
     }
   }
+  if (!(query || mutation)) {
+    throw new Error("Make sure you pass a query or a mutation");
+  }
+}
+
+const executeGraphql = ({
+                          query,
+                          mutation,
+                          variables,
+                          context,
+                          services,
+                          mocks = {},
+                          schema,
+                          serviceMap,
+                          service
+                        }) => {
+  validateArguments(services, service, schema, serviceMap, query, mutation);
+
+  if (services || service) {
+    ({ serviceMap, schema } = setupSchema(services || service));
+  }
 
   setupMocks(serviceMap, mocks);
 

package.json

@@ -36,5 +36,8 @@
     "jest": "^24.8.0",
     "patch-package": "^6.1.2",
     "semantic-release": "^15.13.16"
+  },
+  "dependencies": {
+    "clone": "^2.1.2"
   }
 }

tests/integration.test.js → tests/multipleServices.test.js

@@ -91,9 +91,7 @@ describe("Based on the mocked data from the external service", () => {
         upc: "1",
         name: "Table",
         weight: 10,
-        price: 10,
-        elo: "",
-        __typename: "Product"
+        price: 10
       })
     };
 
@@ -110,9 +108,7 @@ describe("Based on the mocked data from the external service", () => {
         upc: "1",
         name: "Table",
         weight: 10,
-        price: 14000,
-        elo: "",
-        __typename: "Product"
+        price: 14000
       })
     };
 
@@ -141,9 +137,7 @@ test("should allow for using mutations, going across the services", async () =>
       upc: "3",
       name: "Hello",
       weight: 10,
-      price: 14000,
-      elo: "",
-      __typename: "Product"
+      price: 14000
     })
   };
 

tests/singleService.test.js

@@ -0,0 +1,80 @@
+const gql = require("graphql-tag");
+const { executeGraphql } = require("../");
+
+const typeDefs = gql`
+  extend type Product @key(fields: "upc") {
+    upc: String! @external
+    weight: Int @external
+    price: Int @external
+    inStock: Boolean
+    shippingEstimate: Int @requires(fields: "price weight")
+  }
+`;
+
+let inventory = [
+  { upc: "1", inStock: true },
+  { upc: "2", inStock: false },
+  { upc: "3", inStock: true }
+];
+
+const resolvers = {
+  Product: {
+    __resolveReference(object) {
+      return {
+        ...object,
+        ...inventory.find(product => product.upc === object.upc)
+      };
+    },
+    shippingEstimate: object => {
+      if (object.price > 1000) return 0;
+      return object.weight * 0.5;
+    }
+  }
+};
+
+const service = {
+  typeDefs,
+  resolvers
+};
+
+describe("Based on the data from the external service", () => {
+  const query = gql`
+    {
+      _getProduct {
+        inStock
+        shippingEstimate
+      }
+    }
+  `;
+
+  it("should set the shippingEstimate at 0 for an expensive item and retrieve inStock", async () => {
+    const mocks = {
+      Product: () => ({
+        upc: "1",
+        weight: 10,
+        price: 14000,
+      })
+    };
+
+    const result = await executeGraphql({ query, mocks, service });
+
+    expect(result.data._getProduct.shippingEstimate).toEqual(0);
+    expect(result.data._getProduct).toEqual({
+      inStock: true,
+      shippingEstimate: 0
+    });
+  });
+
+  it("should calculate the shipping estimate for cheap item", async () => {
+    const mocks = {
+      Product: () => ({
+        upc: "1",
+        weight: 10,
+        price: 10,
+      })
+    };
+
+    const result = await executeGraphql({ query, mocks, service });
+    expect(result.data._getProduct.shippingEstimate).toEqual(5);
+  });
+});