diff --git a/test/src/test_Buffer.cc b/test/src/test_Buffer.cc
index 96f749b..c93630a 100644
--- a/test/src/test_Buffer.cc
+++ b/test/src/test_Buffer.cc
@@ -152,6 +152,7 @@ TEST(BufferTest, allows_undo_and_redo_of_inserts)
     b.exit_insert_mode();
     EXPECT_EQ(ss("12abc\ndef\nghi\n"), b.get_string());
     EXPECT_EQ(C('a'), **it);
+    EXPECT_EQ(1u, b.m_change_operations.size());
 
     it->go_next_line();
     it->go_right_in_line(false);
@@ -160,11 +161,13 @@ TEST(BufferTest, allows_undo_and_redo_of_inserts)
     b.exit_insert_mode();
     EXPECT_EQ(ss("12abc\nd3ef\nghi\n"), b.get_string());
     EXPECT_EQ(C('e'), **it);
+    EXPECT_EQ(2u, b.m_change_operations.size());
 
     it->go_end_of_line(true);
     b.insert_code_point(*it, C('$'));
     EXPECT_EQ(ss("12abc\nd3ef$\nghi\n"), b.get_string());
     EXPECT_EQ(C('\n'), **it);
+    EXPECT_EQ(3u, b.m_change_operations.size());
 
     it->go_start_of_line();
     EXPECT_EQ(C('d'), **it);
@@ -203,17 +206,20 @@ TEST(BufferTest, allows_undo_and_redo_of_erases)
     b.erase_code_point(*it);
     EXPECT_EQ(ss("bc\ndef\nghi\n"), b.get_string());
     EXPECT_EQ(C('b'), **it);
+    EXPECT_EQ(1u, b.m_change_operations.size());
 
     it->go_next_line();
     it->go_right_in_line(false);
     b.erase_code_point(*it);
     EXPECT_EQ(ss("bc\ndf\nghi\n"), b.get_string());
     EXPECT_EQ(C('f'), **it);
+    EXPECT_EQ(2u, b.m_change_operations.size());
 
     it->go_end_of_line(true);
     b.erase_code_point(*it);
     EXPECT_EQ(ss("bc\ndfghi\n"), b.get_string());
     EXPECT_EQ(C('g'), **it);
+    EXPECT_EQ(3u, b.m_change_operations.size());
 
     it->go_left_in_line();
     EXPECT_EQ(C('f'), **it);