Use proper assertions

Write tests with proper assertions to ensure reliability and maintainability. Follow these guidelines:

1. Check for empty data before proceeding with tests to prevent invalid test conditions:

   string path = cvtest::findDataFile("test_image.png");
   Mat img = imread(path);
   ASSERT_FALSE(img.empty()) << "Cannot open test image: " << path;
   

2. Use ASSERT_* for critical conditions that should halt test execution when failed: ```cpp // Use ASSERT_TRUE for file operations and resource initialization ASSERT_TRUE(fs.isOpened()) « “Failed to open file”;

// Use EXPECT_* for test validations that shouldn’t interrupt the test EXPECT_EQ(dst.cols, 270);

3. **Maintain correct parameter order** in equality assertions with (expected, actual) to generate meaningful error messages:
```cpp
// Correct: ASSERT_EQ(expected_reference, actual_result)
ASSERT_EQ(4, img.channels());
EXPECT_EQ(6, lines[0][0]);

1. Use specialized assertions for common comparisons instead of custom loops:

   // Use instead of manual matrix comparison loops
   EXPECT_MAT_NEAR(src_mat, dst_mat, 0);
   // or
   EXPECT_PRED_FORMAT2(cvtest::MatComparator(0, 0), src_mat, dst_mat);
   

Well-written assertions make tests more reliable, easier to debug, and help identify the exact cause of failures.