From b4303c0d952c7fa9d1eb42693b24ae7e36eda455 Mon Sep 17 00:00:00 2001
From: Martin Huschenbett <martin.huschenbett@posteo.me>
Date: Mon, 24 Feb 2020 11:03:27 +0100
Subject: [PATCH] @daml/react: Add rerendering test for useQuery

Add a test for `useQuery` that ensure that we don't call the JSON API
if the component calling the hook changes without changing the query.

CHANGELOG_BEGIN
CHANGELOG_END
---
 language-support/ts/daml-react/hooks.test.ts | 24 ++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/language-support/ts/daml-react/hooks.test.ts b/language-support/ts/daml-react/hooks.test.ts
index 748216370871..179916d15660 100644
--- a/language-support/ts/daml-react/hooks.test.ts
+++ b/language-support/ts/daml-react/hooks.test.ts
@@ -69,6 +69,7 @@ describe('useQuery', () => {
     const resolvent1 = ['foo'];
     const resolvent2 = ['bar'];
 
+    // First rendering works?
     mockQuery.mockReturnValueOnce(Promise.resolve(resolvent1));
     const {result, waitForNextUpdate} = renderDamlHook(() => {
       const [query, setQuery] = useState(query1);
@@ -83,6 +84,7 @@ describe('useQuery', () => {
     await waitForNextUpdate();
     expect(result.current.queryResult).toEqual({contracts: resolvent1, loading: false});
 
+    // Change to query triggers another call to JSON API?
     mockQuery.mockReturnValueOnce(Promise.resolve(resolvent2));
     act(() => result.current.setQuery(query2));
     expect(mockQuery).toHaveBeenCalledTimes(1);
@@ -93,4 +95,26 @@ describe('useQuery', () => {
     await waitForNextUpdate();
     expect(result.current.queryResult).toEqual({contracts: resolvent2, loading: false});
   });
+
+  test('rerendering without query change', async () => {
+    const query = 'query';
+    const resolvent = ['foo'];
+
+    // First rendering works?
+    mockQuery.mockReturnValueOnce(Promise.resolve(resolvent));
+    const {result, waitForNextUpdate} = renderDamlHook(() => {
+      const setState = useState('state')[1];
+      const queryResult = useQuery(Foo, () => ({query}), [query]);
+      return {queryResult, query, setState};
+    });
+    expect(mockQuery).toHaveBeenCalledTimes(1);
+    mockQuery.mockClear();
+    await waitForNextUpdate();
+    expect(result.current.queryResult).toEqual({contracts: resolvent, loading: false});
+
+    // Change to unrelated state does _not_ trigger another call to JSON API?
+    act(() => result.current.setState('new-state'));
+    expect(mockQuery).not.toHaveBeenCalled();
+    expect(result.current.queryResult).toEqual({contracts: resolvent, loading: false});
+  });
 });