From 269f71fee3af1243f6f095474f99d1e4400a7fb3 Mon Sep 17 00:00:00 2001
From: "Timothy J. Wood" <tjw@omnigroup.com>
Date: Fri, 17 May 2019 16:32:26 -0700
Subject: [PATCH] Add a random shuffle test. Add a specific case generated by
 the random test that crashes with an out-of-bounds access.

---
 Tests/DifferTests/DiffTests.swift | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Tests/DifferTests/DiffTests.swift b/Tests/DifferTests/DiffTests.swift
index b701544..3f6dcc7 100644
--- a/Tests/DifferTests/DiffTests.swift
+++ b/Tests/DifferTests/DiffTests.swift
@@ -123,4 +123,33 @@ class DiffTests: XCTestCase {
             .extendedDiff(to)
             .reduce("") { $0 + $1.debugDescription }
     }
+
+
+    func testRandomReorder() {
+        (0..<1000).forEach { _ in
+            let count = Int.random(in: 5..<10)
+            let originalOrder = (0..<count).map { $0 }
+            let updatedOrder = originalOrder.shuffled()
+
+            print("originalOrder \(originalOrder), updatedOrder \(updatedOrder)")
+
+            let changes = extendedPatch(from: originalOrder, to: updatedOrder)
+            let result = originalOrder.apply(changes)
+
+            XCTAssertEqual(updatedOrder, result)
+        }
+    }
+
+    // Specific cases generated by testRandomReorder that crash or produced incorrect results previously.
+
+    func testRandomReorder1() {
+        let originalOrder = [0, 1, 2, 3, 4]
+        let updatedOrder = [4, 3, 2, 0, 1]
+
+        let changes = extendedPatch(from: originalOrder, to: updatedOrder)
+        let result = originalOrder.apply(changes)
+
+        XCTAssertEqual(updatedOrder, result)
+    }
+
 }