Fixed another code smell and added report.md

Author: saisandeepramavath

courseProjectDocs/static-analysis/report.md

@@ -0,0 +1,103 @@
+# Static Analysis Report
+
+## Tool Used
+
+**Tool:** ruff v0.14.3  
+**Command:** `ruff check pandas/util/_validators.py --select ALL --ignore E501,D203,D213`  
+**Target File:** `pandas/util/_validators.py`
+
+## Key Findings
+
+Ruff identified **88 code smells** in the target file across multiple categories:
+
+- **EM102 (25 instances):** F-string literals in exceptions - should assign to variable first
+- **TRY003 (15 instances):** Long exception messages outside exception class
+- **ANN001 (23 instances):** Missing type annotations for function arguments
+- **D205/D401 (12 instances):** Docstring formatting issues
+- **PLC0415 (1 instance):** Import not at top-level of file
+- **SIM102 (1 instance):** Nested if statements can be combined
+- **FBT001/FBT002 (8 instances):** Boolean-typed positional arguments
+
+Total: **88 code smells detected**
+
+## Fixes Summary
+
+### Fix #1: F-String in Exception (EM102)
+**Assigned to:** Sandeep Ramavath  
+**Location:** Line 292 in `pandas/util/_validators.py`  
+**Issue:** Exception uses f-string literal directly instead of assigning to variable first
+
+**Before:**
+```python
+def validate_bool_kwarg_nullable(value, arg_name: str) -> None:
+    if (
+        value is lib.no_default
+        or isinstance(value, bool)
+        or value is None
+        or value is NA
+        or (lib.is_float(value) and np.isnan(value))
+    ):
+        return
+    raise ValueError(f"{arg_name} must be None, pd.NA, np.nan, True, or False; got {value}")
+```
+
+**After:**
+```python
+def validate_bool_kwarg_nullable(value, arg_name: str) -> None:
+    if (
+        value is lib.no_default
+        or isinstance(value, bool)
+        or value is None
+        or value is NA
+        or (lib.is_float(value) and np.isnan(value))
+    ):
+        return
+    msg = f"{arg_name} must be None, pd.NA, np.nan, True, or False; got {value}"
+    raise ValueError(msg)
+```
+
+**Rationale:** Assigning error messages to variables before raising exceptions improves code maintainability, makes testing easier, and follows Python best practices for exception handling.
+
+---
+
+### Fix #2: Import Not at Top-Level (PLC0415)
+**Assigned to:** Nithikesh Bobbili  
+**Location:** Line 314 in `pandas/util/_validators.py`  
+**Issue:** Import statement inside function body instead of at module level
+
+**Before:**
+```python
+def validate_fillna_kwargs(value, method, validate_scalar_dict_value: bool = True):
+    """Validate the keyword arguments to 'fillna'.
+    ...
+    """
+    from pandas.core.missing import clean_fill_method  # Import inside function
+
+    if value is None and method is None:
+        raise ValueError("Must specify a fill 'value' or 'method'.")
+    if value is None and method is not None:
+        method = clean_fill_method(method)
+    # ...
+```
+
+**After:**
+```python
+# At module level (top of file, after line 20):
+from pandas.core.missing import clean_fill_method
+
+# ...
+
+def validate_fillna_kwargs(value, method, validate_scalar_dict_value: bool = True):
+    """Validate the keyword arguments to 'fillna'.
+    ...
+    """
+    if value is None and method is None:
+        raise ValueError("Must specify a fill 'value' or 'method'.")
+    if value is None and method is not None:
+        method = clean_fill_method(method)
+    # ...
+```
+
+**Rationale:** Module-level imports are executed once at module load time rather than every function call, improving performance. It also makes dependencies more visible and follows PEP 8 conventions.
+
+---