From c8ce4650f0908b8d9d7bf7986f0eae1bf7cae2d5 Mon Sep 17 00:00:00 2001
From: Rodrigo Tobar <rtobar@icrar.org>
Date: Tue, 23 Jul 2024 15:01:30 +0800
Subject: [PATCH] Add tests for different chunk sizes and offsets

The latter in particular is useful to make sure that the different
memory alignment code paths in the C code are correct.

Signed-off-by: Rodrigo Tobar <rtobar@icrar.org>
---
 CHANGELOG.md        |  1 +
 test/test_crc32c.py | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8716776..e2c34f8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 * Adding explicit fallthrough annotations
   in several ``switch`` C statements
   for clarity, and to avoid potential warnings (#46).
+* Run test against different memory alignments.
 
 ## [2.4.1]
 
diff --git a/test/test_crc32c.py b/test/test_crc32c.py
index 7b9e579..480610a 100644
--- a/test/test_crc32c.py
+++ b/test/test_crc32c.py
@@ -45,6 +45,11 @@ def ushort_as_bytes(x):
 def uchar_as_bytes(c):
     return struct.pack('<B', c)
 
+def batched(x, size):
+    length = len(x)
+    for i in range(0, length, size):
+        yield x[i: min(i + size, length)]
+
 if sys.version_info[0] == 2:
     def as_individual_bytes(x):
         return x
@@ -120,6 +125,21 @@ def test_piece_by_piece(self):
             c = crc32c.crc32c(x, c)
         self.assertEqual(self.checksum, c)
 
+    def test_by_different_chunk_lenghts(self):
+        for chunk_size in range(1, 33):
+            c = 0
+            for chunk in batched(self.val, chunk_size):
+                c = crc32c.crc32c(bytes(chunk), c)
+            self.assertEqual(self.checksum, c)
+
+    def test_by_different_memory_offsets(self):
+        for offset in range(16):
+            val = memoryview(self.val)
+            c = crc32c.crc32c(val[0:offset])
+            c = crc32c.crc32c(val[offset:], c)
+            self.assertEqual(self.checksum, c, "Invalid checksum when splitting at offset %d" % offset)
+
+
 # Generate the actual unittest classes for each of the testing values
 if crc32c is not None:
     for name, val, checksum in (numbers1, numbers2, numbers3, phrase, long_phrase):