Add tests on companies page (#155)

front/src/testing/mockedClient.ts

@@ -0,0 +1,16 @@
+import { ApolloClient, InMemoryCache } from '@apollo/client';
+
+export const mockedClient = new ApolloClient({
+  uri: process.env.REACT_APP_API_URL,
+  cache: new InMemoryCache(),
+  defaultOptions: {
+    watchQuery: {
+      fetchPolicy: 'no-cache',
+      errorPolicy: 'all',
+    },
+    query: {
+      fetchPolicy: 'no-cache',
+      errorPolicy: 'all',
+    },
+  },
+});