From a075eda079b2f837a125298466e77db858e369d4 Mon Sep 17 00:00:00 2001
From: Jerel Miller <jmiller@newrelic.com>
Date: Thu, 11 Jun 2020 11:52:21 -0700
Subject: [PATCH] feat: Add a splitUsing utility function

---
 src/utils/__tests__/splitUsing.js | 37 +++++++++++++++++++++++++++++++
 src/utils/splitUsing.js           | 20 +++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 src/utils/__tests__/splitUsing.js
 create mode 100644 src/utils/splitUsing.js

diff --git a/src/utils/__tests__/splitUsing.js b/src/utils/__tests__/splitUsing.js
new file mode 100644
index 000000000..a5b864f61
--- /dev/null
+++ b/src/utils/__tests__/splitUsing.js
@@ -0,0 +1,37 @@
+import splitUsing from '../splitUsing';
+
+test('splits the list into chunks at the indexes where the predicate is true', () => {
+  const list = [1, 2, 3, 2, 5, 5];
+
+  const result = splitUsing(list, (num) => num === 2);
+
+  expect(result).toEqual([
+    [1, 2],
+    [3, 2],
+    [5, 5],
+  ]);
+});
+
+test('returns empty list if there are no items', () => {
+  const list = [];
+
+  const result = splitUsing(list, () => true);
+
+  expect(result).toEqual([]);
+});
+
+test('handles list where no items satisfy the predicate', () => {
+  const list = [0, 1, 2, 3];
+
+  const result = splitUsing(list, (num) => num === 10);
+
+  expect(result).toEqual([[0, 1, 2, 3]]);
+});
+
+test('handles list where all items satisfy the predicate', () => {
+  const list = [0, 0, 0, 0];
+
+  const result = splitUsing(list, (num) => num === 0);
+
+  expect(result).toEqual([[0], [0], [0], [0]]);
+});
diff --git a/src/utils/splitUsing.js b/src/utils/splitUsing.js
new file mode 100644
index 000000000..49f13797c
--- /dev/null
+++ b/src/utils/splitUsing.js
@@ -0,0 +1,20 @@
+const splitUsing = (list, predicate) => {
+  const { groups, items } = list.reduce(
+    ({ groups, items }, item) => {
+      if (predicate(item)) {
+        return { groups: groups.concat([items.concat(item)]), items: [] };
+      }
+
+      return { groups: groups, items: items.concat(item) };
+    },
+    { groups: [], items: [] }
+  );
+
+  if (items.length > 1) {
+    return [...groups, items];
+  }
+
+  return groups;
+};
+
+export default splitUsing;