From 2ea7d45f6e309608a47d39bee8096324e1f632fd Mon Sep 17 00:00:00 2001
From: Mattias Fredriksson <mattias-fredriksson91@hotmail.se>
Date: Fri, 18 Jul 2025 09:54:20 +0200
Subject: [PATCH] Cleanup: Improve output from OBJ export tests

Improves output from tests comparing export results to the golden
example file:

- Prints which of the files that are empty and/or has no newline.
- Prints a message when there is a mismatch in file length.
- Clarifies that the inner compare loop only compares up to shortest string.
- Prints the name of the failing golden file, indicating if it was the obj
  or mtl file that failed.

Pull Request: https://projects.blender.org/blender/blender/pulls/141958
---
 .../wavefront_obj/tests/obj_exporter_tests.cc | 33 ++++++++++++++-----
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
index 0056d43a20a..caf980b6526 100644
--- a/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
+++ b/source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc
@@ -243,12 +243,23 @@ static bool strings_equal_after_first_lines(const std::string &a, const std::str
   const size_t b_len = b.size();
   const size_t a_next = a.find_first_of('\n');
   const size_t b_next = b.find_first_of('\n');
-  if (a_next == std::string::npos || b_next == std::string::npos) {
-    printf("Couldn't find newline in one of args\n");
+  if (a_next == std::string::npos) {
+    printf("No newline found in evaluated string\n");
     return false;
   }
-  if (a.compare(a_next, a_len - a_next, b, b_next, b_len - b_next) != 0) {
-    for (int i = 0; i < a_len - a_next && i < b_len - b_next; ++i) {
+  if (b_next == std::string::npos) {
+    printf("No newline found in the golden string\n");
+    return false;
+  }
+  const size_t a_sublen = a_len - a_next;
+  const size_t b_sublen = b_len - b_next;
+  if (a_sublen != b_sublen) {
+    printf("Mismatching string length, evaluated contains %zu chars, while golden has %zu\n",
+           a_sublen,
+           b_sublen);
+  }
+  if (a.compare(a_next, a_sublen, b, b_next, b_sublen) != 0) {
+    for (int i = 0; i < std::min(a_sublen, b_sublen); ++i) {
       if (a[a_next + i] != b[b_next + i]) {
         printf("Difference found at pos %zu of a\n", a_next + i);
         printf("a: %s ...\n", a.substr(a_next + i, 100).c_str());
@@ -293,8 +304,11 @@ class OBJExportRegressionTest : public OBJExportTest {
 
     std::string golden_str = read_temp_file_in_string(golden_file_path);
     bool are_equal = strings_equal_after_first_lines(output_str, golden_str);
-    if (save_failing_test_output && !are_equal) {
-      printf("failing test output in %s\n", out_file_path.c_str());
+    if (!are_equal) {
+      printf("failed test for file: %s\n", golden_file_path.c_str());
+      if (save_failing_test_output) {
+        printf("failing test output in %s\n", out_file_path.c_str());
+      }
     }
     ASSERT_TRUE(are_equal);
     if (!save_failing_test_output || are_equal) {
@@ -307,8 +321,11 @@ class OBJExportRegressionTest : public OBJExportTest {
                                          golden_mtl;
       std::string golden_mtl_str = read_temp_file_in_string(golden_mtl_file_path);
       are_equal = strings_equal_after_first_lines(output_mtl_str, golden_mtl_str);
-      if (save_failing_test_output && !are_equal) {
-        printf("failing test output in %s\n", out_mtl_file_path.c_str());
+      if (!are_equal) {
+        printf("failed test for mtl file: %s\n", golden_mtl_file_path.c_str());
+        if (save_failing_test_output) {
+          printf("failing test output in %s\n", out_mtl_file_path.c_str());
+        }
       }
       ASSERT_TRUE(are_equal);
       if (!save_failing_test_output || are_equal) {