Limit code snippet length of generic renderer (#1267)

Author: Zain-Mahmoud

CHANGELOG.md

@@ -20,6 +20,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - Added markdown rendering to display code in error messages
 - Improved RI checking to raise a warning when a `NameError` is raised and the missing name matches an instance attribute, and is due to an omitted `self.` in the RI.
 - Extended `AccumulationTable` class to support multiple loops in sequence within the same context manager
+- Added a solution to prevent possible large snippets created by the `render_generic` function
 
 ### 💫 New checkers
 

python_ta/reporters/node_printers.py

@@ -36,11 +36,25 @@ def render_generic(msg, node=None, source_lines=None, config=None):
                 source_lines[start_line - 1],
             )
         else:
-            yield (start_line, slice(start_col, None), LineType.ERROR, source_lines[start_line - 1])
-            yield from (
-                (line, slice(None, None), LineType.ERROR, source_lines[line - 1])
-                for line in range(start_line + 1, end_line)
+            num_lines = end_line - start_line
+            half_threshold = MAX_SNIPPET_LINES // 2
+            yield (
+                start_line,
+                slice(start_col, None),
+                LineType.ERROR,
+                source_lines[start_line - 1],
             )
+            for line in range(start_line + 1, start_line + min(half_threshold, num_lines)):
+                yield (line, slice(None, None), LineType.ERROR, source_lines[line - 1])
+
+            if end_line - start_line > MAX_SNIPPET_LINES:
+                yield ("", slice(None, None), LineType.OTHER, "...")
+
+            for line in range(
+                end_line - min(half_threshold, num_lines - half_threshold) + 1, end_line
+            ):
+                yield (line, slice(None, None), LineType.ERROR, source_lines[line - 1])
+
             yield (end_line, slice(None, end_col), LineType.ERROR, source_lines[end_line - 1])
 
         # Display up to 2 lines after node for context:

tests/fixtures/sample_dir/custom_checkers/e9920_unnecessary_f_string.py

@@ -0,0 +1,31 @@
+"""Examples for e9920_unnecessary_f_string_checker to demonstrate reduction of snippet length"""
+
+
+def demo_function() -> str:
+    """
+    Demonstrates e9920_unnecessary_f_string_checker
+    """
+    x = "hello"
+    a = f"{x}"  # error on this line
+
+    b = f"{x =}"  # no error on this line
+
+    c = f"{x + ' world' 
+           
+           
+           
+           
+           
+           + 'hi'
+           
+           
+           
+           
+
+
+
+           
+           
+           }"  # error on this line
+
+    return x + a + b + c