1 files changed, 46 insertions, 0 deletions
diff --git a/spec/frontend/__helpers__/test_apollo_link.js b/spec/frontend/__helpers__/test_apollo_link.js
new file mode 100644
index 00000000000..dde3a4e99bb
--- /dev/null
+++ b/spec/frontend/__helpers__/test_apollo_link.js
@@ -0,0 +1,46 @@
+import { InMemoryCache } from 'apollo-cache-inmemory';
+import { ApolloClient } from 'apollo-client';
+import { ApolloLink } from 'apollo-link';
+import gql from 'graphql-tag';
+
+const FOO_QUERY = gql`
+  query {
+    foo
+  }
+`;
+
+/**
+ * This function returns a promise that resolves to the final operation after
+ * running an ApolloClient query with the given ApolloLink
+ *
+ * @typedef {Object} TestApolloLinkOptions
+ * @property {Object} context the default context object sent along the ApolloLink chain
+ *
+ * @param {ApolloLink} subjectLink the ApolloLink which is under test
+ * @param {TestApolloLinkOptions} options contains options to send a long with the query
+ *
+ * @returns Promise resolving to the resulting operation after running the subjectLink
+ */
+export const testApolloLink = (subjectLink, options = {}) =>
+  new Promise((resolve) => {
+    const { context = {} } = options;
+
+    // Use the terminating link to capture the final operation and resolve with this.
+    const terminatingLink = new ApolloLink((operation) => {
+      resolve(operation);
+
+      return null;
+    });
+
+    const client = new ApolloClient({
+      link: ApolloLink.from([subjectLink, terminatingLink]),
+      // cache is a required option
+      cache: new InMemoryCache(),
+    });
+
+    // Trigger a query so the ApolloLink chain will be executed.
+    client.query({
+      context,
+      query: FOO_QUERY,
+    });
+  });