merge: test CR/LF conflicts for CR/LF files

Ensure that when the files being merged have CR/LF line endings that the
conflict markers produced in the conflict file also have CR/LF line
endings.

tests/merge/files.c

@@ -377,3 +377,51 @@ void test_merge_files__handles_binaries_when_favored(void)
 
 	git_merge_file_result_free(&result);
 }
+
+void test_merge_files__crlf_conflict_markers_for_crlf_files(void)
+{
+	git_merge_file_input ancestor = GIT_MERGE_FILE_INPUT_INIT,
+		ours = GIT_MERGE_FILE_INPUT_INIT,
+		theirs = GIT_MERGE_FILE_INPUT_INIT;
+	git_merge_file_options opts = GIT_MERGE_FILE_OPTIONS_INIT;
+	git_merge_file_result result = {0};
+
+	const char *expected =
+		"<<<<<<< file.txt\r\nThis file\r\ndoes, too.\r\n"
+		"=======\r\nAnd so does\r\nthis one.\r\n>>>>>>> file.txt\r\n";
+	size_t expected_len = strlen(expected);
+
+	const char *expected_diff3 =
+		"<<<<<<< file.txt\r\nThis file\r\ndoes, too.\r\n"
+		"||||||| file.txt\r\nThis file has\r\nCRLF line endings.\r\n"
+		"=======\r\nAnd so does\r\nthis one.\r\n>>>>>>> file.txt\r\n";
+	size_t expected_diff3_len = strlen(expected_diff3);
+
+	ancestor.ptr = "This file has\r\nCRLF line endings.\r\n";
+	ancestor.size = 35;
+	ancestor.path = "file.txt";
+	ancestor.mode = 0100644;
+
+	ours.ptr = "This file\r\ndoes, too.\r\n";
+	ours.size = 23;
+	ours.path = "file.txt";
+	ours.mode = 0100644;
+
+	theirs.ptr = "And so does\r\nthis one.\r\n";
+	theirs.size = 24;
+	theirs.path = "file.txt";
+	theirs.mode = 0100644;
+
+	cl_git_pass(git_merge_file(&result, &ancestor, &ours, &theirs, &opts));
+	cl_assert_equal_i(0, result.automergeable);
+	cl_assert_equal_i(expected_len, result.len);
+	cl_assert(memcmp(expected, result.ptr, expected_len) == 0);
+	git_merge_file_result_free(&result);
+
+	opts.flags |= GIT_MERGE_FILE_STYLE_DIFF3;
+	cl_git_pass(git_merge_file(&result, &ancestor, &ours, &theirs, &opts));
+	cl_assert_equal_i(0, result.automergeable);
+	cl_assert_equal_i(expected_diff3_len, result.len);
+	cl_assert(memcmp(expected_diff3, result.ptr, expected_len) == 0);
+	git_merge_file_result_free(&result);
+}