diff --git a/tests/unit/file.c b/tests/unit/file.c
index 1aec04f..fc13064 100644
--- a/tests/unit/file.c
+++ b/tests/unit/file.c
@@ -109,6 +109,20 @@ COSMS_CORE_TEST_TEST(file_open,
             }
         }
     )
+
+    COSMS_CORE_TEST_SUB_TEST(opening non-existing file for reading,
+        struct cosms_core_file file;
+        CosmsCoreFileError error = cosms_core_file_open(&file, "non-existing-file.cosms", COSMS_CORE_FILE_MODE_READ);
+        if (error != COSMS_CORE_FILE_NOT_FOUND) {
+            cosms_core_test_sub_test_error = cosms_core_file_error_string(error);
+            if (error == COSMS_CORE_FILE_OK) {
+                error = cosms_core_file_close(&file);
+                if (error != COSMS_CORE_FILE_OK) {
+                    cosms_core_test_sub_test_error = cosms_core_file_error_string(error);
+                }
+            }
+        }
+    )
 )
 
 COSMS_CORE_TEST_TEST(file_close,