feat(SubscriptionOperation): only complete Queries and Mutations

BREAKING CHANGE: subscription observables must be manually completed by the `complete()` method.

Author: Frozen-byte

.changeset/perfect-buckets-drum.md

@@ -0,0 +1,7 @@
+---
+'apollo-angular': major
+---
+
+added a `complete()` method for `TestOperation` object to cancel subscriptions after `flush()`  
+
+BREAKING CHANGE: subscription observables must be manually completed by the `complete()` method. 

packages/apollo-angular/testing/src/operation.ts

@@ -1,10 +1,9 @@
-import { ExecutionResult, GraphQLError } from 'graphql';
+import { ExecutionResult, GraphQLError, Kind, OperationTypeNode } from 'graphql';
 import { Observer } from 'rxjs';
 import { ApolloError, FetchResult, Operation as LinkOperation } from '@apollo/client/core';
+import { getMainDefinition } from '@apollo/client/utilities';
 
-function isApolloError(error: unknown): error is ApolloError {
-  return !!error && error.hasOwnProperty('graphQLErrors');
-}
+const isApolloError = (err: any): err is ApolloError => err && err.hasOwnProperty('graphQLErrors');
 
 export type Operation = LinkOperation & {
   clientName: string;
@@ -22,10 +21,22 @@ export class TestOperation<T = { [key: string]: any }> {
     } else {
       const fetchResult = result ? { ...result } : result;
       this.observer.next(fetchResult);
-      this.observer.complete();
+
+      const definition = getMainDefinition(this.operation.query);
+
+      if (
+        definition.kind === Kind.OPERATION_DEFINITION &&
+        definition.operation !== OperationTypeNode.SUBSCRIPTION
+      ) {
+        this.complete();
+      }
     }
   }
 
+  public complete() {
+    this.observer.complete();
+  }
+
   public flushData(data: T | null): void {
     this.flush({
       data,

packages/apollo-angular/testing/tests/operation.spec.ts

@@ -1,4 +1,4 @@
-import { ApolloLink, execute, gql } from '@apollo/client/core';
+import { ApolloLink, execute, FetchResult, gql } from '@apollo/client/core';
 import { ApolloTestingBackend } from '../src/backend';
 import { buildOperationForLink } from './utils';
 
@@ -9,6 +9,20 @@ const testQuery = gql`
     }
   }
 `;
+const testSubscription = gql`
+  subscription newHeroes {
+    heroes {
+      name
+    }
+  }
+`;
+const testMutation = gql`
+  mutation addHero($hero: String!) {
+    addHero(hero: $hero) {
+      name
+    }
+  }
+`;
 
 describe('TestOperation', () => {
   let mock: ApolloTestingBackend;
@@ -52,4 +66,104 @@ describe('TestOperation', () => {
       heroes: [],
     });
   });
+
+  test('should leave the operation open for a subscription', done => {
+    const operation = buildOperationForLink(testSubscription, {});
+    const emittedResults: FetchResult[] = [];
+
+    execute(link, operation).subscribe({
+      next(result) {
+        emittedResults.push(result);
+      },
+      complete() {
+        expect(emittedResults).toEqual([
+          {
+            data: {
+              heroes: ['first Hero'],
+            },
+          },
+          {
+            data: {
+              heroes: ['second Hero'],
+            },
+          },
+        ]);
+        done();
+      },
+    });
+
+    const testOperation = mock.expectOne(testSubscription);
+
+    testOperation.flushData({
+      heroes: ['first Hero'],
+    });
+
+    testOperation.flushData({
+      heroes: ['second Hero'],
+    });
+
+    testOperation.complete();
+  });
+
+  test('should close the operation after a query', done => {
+    const operation = buildOperationForLink(testQuery, {});
+    const emittedResults: FetchResult[] = [];
+
+    execute(link, operation).subscribe({
+      next(result) {
+        emittedResults.push(result);
+      },
+      complete() {
+        expect(emittedResults).toEqual([
+          {
+            data: {
+              heroes: ['first Hero'],
+            },
+          },
+        ]);
+        done();
+      },
+    });
+
+    const testOperation = mock.expectOne(testQuery);
+
+    testOperation.flushData({
+      heroes: ['first Hero'],
+    });
+
+    testOperation.flushData({
+      heroes: ['second Hero'],
+    });
+  });
+
+  test('should close the operation after a mutation', done => {
+    const operation = buildOperationForLink(testMutation, { hero: 'firstHero' });
+    const emittedResults: FetchResult[] = [];
+
+    execute(link, operation).subscribe({
+      next(result) {
+        emittedResults.push(result);
+      },
+      complete() {
+        expect(emittedResults).toEqual([
+          {
+            data: {
+              heroes: ['first Hero'],
+            },
+          },
+        ]);
+        done();
+      },
+    });
+
+    const testOperation = mock.expectOne(testMutation);
+
+    testOperation.flushData({
+      heroes: ['first Hero'],
+    });
+
+    testOperation.flushData({
+      heroes: ['second Hero'],
+    });
+  });
 });

website/src/pages/docs/development-and-testing/testing.mdx

@@ -230,6 +230,7 @@ It's an object returned by `expectOne` and `match` methods.
   ApolloError instance
 - `networkError(error: Error): void{:ts}` - to flush an operation with a network error
 - `graphqlErrors(errors: GraphQLError[]): void{:ts}` - to flush an operation with graphql errors
+- `complete(): void{:ts}` - manually complete the connection, useful for subscription based testing
 
 ## Using Named Clients