From 3935e661fe457ae3bbc3a5b0aec2b4b695b555e5 Mon Sep 17 00:00:00 2001
From: Amir Bandeali <abandeali1@gmail.com>
Date: Tue, 3 Sep 2019 17:05:32 -0700
Subject: [PATCH] Add more writeLength tests

---
 contracts/utils/contracts/test/TestLibBytes.sol | 14 ++++++++++++++
 contracts/utils/test/lib_bytes.ts               | 14 ++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/contracts/utils/contracts/test/TestLibBytes.sol b/contracts/utils/contracts/test/TestLibBytes.sol
index ab316b08d8..b2f39e5fcc 100644
--- a/contracts/utils/contracts/test/TestLibBytes.sol
+++ b/contracts/utils/contracts/test/TestLibBytes.sol
@@ -325,4 +325,18 @@ contract TestLibBytes {
         b.writeLength(length);
         return b;
     }
+
+    function assertBytesUnchangedAfterLengthReset(
+        bytes memory b,
+        uint256 tempLength
+    )
+        public
+        pure
+    {
+        uint256 length = b.length;
+        bytes memory bCopy = b.slice(0, length);
+        b.writeLength(tempLength);
+        b.writeLength(length);
+        assert(b.equals(bCopy));
+    }
 }
diff --git a/contracts/utils/test/lib_bytes.ts b/contracts/utils/test/lib_bytes.ts
index ace87b530e..5efe1dc113 100644
--- a/contracts/utils/test/lib_bytes.ts
+++ b/contracts/utils/test/lib_bytes.ts
@@ -1131,6 +1131,20 @@ describe('LibBytes', () => {
             );
             expect(result).to.eq(`${byteArrayLongerThan32Bytes}${byteArrayLongerThan32Bytes.slice(2)}`);
         });
+        it('should result in the same byte array if length is reduced and reset', async () => {
+            const byteLen = (byteArrayLongerThan32Bytes.length - 2) / 2;
+            const tempByteLen = new BigNumber(byteLen).dividedToIntegerBy(2);
+            return expect(
+                libBytes.assertBytesUnchangedAfterLengthReset.callAsync(byteArrayLongerThan32Bytes, tempByteLen),
+            ).to.be.fulfilled('');
+        });
+        it('should result in the same byte array if length is increased and reset', async () => {
+            const byteLen = (byteArrayLongerThan32Bytes.length - 2) / 2;
+            const tempByteLen = new BigNumber(byteLen).multipliedBy(2);
+            return expect(
+                libBytes.assertBytesUnchangedAfterLengthReset.callAsync(byteArrayLongerThan32Bytes, tempByteLen),
+            ).to.be.fulfilled('');
+        });
     });
 });
 // tslint:disable:max-file-line-count