From 5fe3e9a44a3812a06303fbf3fd68b95d0a46bb52 Mon Sep 17 00:00:00 2001
From: Pascal Hartig <realpassy@fb.com>
Date: Wed, 13 May 2020 07:46:48 -0700
Subject: [PATCH] Add test for LowPassFilter

Summary: Eating my own dogfood.

Reviewed By: mweststrate

Differential Revision: D21545655

fbshipit-source-id: 1e2690478ad8a986915a98a8275a168fa4c3a23f
---
 .../utils/__tests__/LowPassFilter.node.tsx    | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 desktop/app/src/utils/__tests__/LowPassFilter.node.tsx

diff --git a/desktop/app/src/utils/__tests__/LowPassFilter.node.tsx b/desktop/app/src/utils/__tests__/LowPassFilter.node.tsx
new file mode 100644
index 000000000..44538775a
--- /dev/null
+++ b/desktop/app/src/utils/__tests__/LowPassFilter.node.tsx
@@ -0,0 +1,46 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import LowPassFilter from '../LowPassFilter';
+
+test('hasFullBuffer', () => {
+  const lpf = new LowPassFilter();
+  expect(lpf.hasFullBuffer()).toBeFalsy();
+
+  lpf.push(1);
+  lpf.push(2);
+  lpf.push(3);
+  lpf.push(4);
+  lpf.push(5);
+
+  expect(lpf.hasFullBuffer()).toBeTruthy();
+});
+
+test('push on full buffer returns shifted value', () => {
+  const lpf = new LowPassFilter();
+  expect(lpf.push(1)).toBe(0);
+  expect(lpf.push(2)).toBe(0);
+  expect(lpf.push(3)).toBe(0);
+  expect(lpf.push(4)).toBe(0);
+  expect(lpf.push(5)).toBe(0);
+  expect(lpf.push(6)).toBe(1);
+  expect(lpf.push(7)).toBe(2);
+});
+
+test('next returns smoothed value', () => {
+  const lpf = new LowPassFilter();
+  expect(lpf.next(1)).toBe(0.9);
+  expect(lpf.next(2)).toBe(1.881);
+});
+
+test('next returns smoothed value with custom smoothing', () => {
+  const lpf = new LowPassFilter(0.5);
+  expect(lpf.next(1)).toBe(0.5);
+  expect(lpf.next(2)).toBe(1.125);
+});