diff --git a/codecov.yml b/codecov.yml
new file mode 100644
index 0000000..59ae75c
--- /dev/null
+++ b/codecov.yml
@@ -0,0 +1,13 @@
+# https://docs.codecov.io/docs/common-recipe-list
+# https://docs.codecov.io/docs/commit-status#patch-status
+
+coverage:
+  status:
+
+    project:
+      default:
+        target: 90%
+
+    patch:
+      default:
+        informational: true
diff --git a/cratedb_sqlparse_py/cratedb_sqlparse/__init__.py b/cratedb_sqlparse_py/cratedb_sqlparse/__init__.py
index d1ba64b..c9b943b 100644
--- a/cratedb_sqlparse_py/cratedb_sqlparse/__init__.py
+++ b/cratedb_sqlparse_py/cratedb_sqlparse/__init__.py
@@ -1,4 +1,3 @@
-from .parser import sqlparse, ParsingException
-
-__all__ = ['sqlparse', 'ParsingException']
+from .parser import ParsingException, sqlparse
 
+__all__ = ["sqlparse", "ParsingException"]
diff --git a/cratedb_sqlparse_py/cratedb_sqlparse/generated_parser/AbstractSqlBaseLexer.py b/cratedb_sqlparse_py/cratedb_sqlparse/generated_parser/AbstractSqlBaseLexer.py
index 3422eb4..e3282d2 100644
--- a/cratedb_sqlparse_py/cratedb_sqlparse/generated_parser/AbstractSqlBaseLexer.py
+++ b/cratedb_sqlparse_py/cratedb_sqlparse/generated_parser/AbstractSqlBaseLexer.py
@@ -3,8 +3,11 @@
 
 class AbstractSqlBaseLexer(Lexer):
     """
-    Automatically generated by Antlr4. It was added originally in CrateDB (https://github.com/crate/crate/commit/8e7cfd7c4a05fc27de8ce71af9165b98c986d883)
-    to implement $ strings, e.g: "SELECT $my friend's house$", we cannot do the same since it also generates invalid python syntax:
+    Automatically generated by Antlr4.
+
+    It was added originally in CrateDB (https://github.com/crate/crate/commit/8e7cfd7c4a05fc27de8ce71af9165b98c986d883)
+    to implement $ strings, e.g: "SELECT $my friend's house$", we cannot do the same since it also generates invalid
+    Python syntax:
 
     # SqlBaseLexer.py
     class SqlBaseLexer(AbstractSqlBaseLexer):
diff --git a/cratedb_sqlparse_py/cratedb_sqlparse/parser.py b/cratedb_sqlparse_py/cratedb_sqlparse/parser.py
index 875511d..a272f07 100644
--- a/cratedb_sqlparse_py/cratedb_sqlparse/parser.py
+++ b/cratedb_sqlparse_py/cratedb_sqlparse/parser.py
@@ -1,10 +1,10 @@
 from typing import List
 
-from antlr4 import InputStream, CommonTokenStream, Token
+from antlr4 import CommonTokenStream, InputStream, Token
 from antlr4.error.ErrorListener import ErrorListener
 
-from cratedb_sqlparse.generated_parser.SqlBaseParser import SqlBaseParser
 from cratedb_sqlparse.generated_parser.SqlBaseLexer import SqlBaseLexer
+from cratedb_sqlparse.generated_parser.SqlBaseParser import SqlBaseParser
 
 
 def BEGIN_DOLLAR_QUOTED_STRING_action(self, localctx, actionIndex):
@@ -17,9 +17,10 @@ def END_DOLLAR_QUOTED_STRING_action(self, localctx, actionIndex):
         self.tags.pop()
 
 
-def END_DOLLAR_QUOTED_STRING_sempred(self, localctx, predIndex):
+def END_DOLLAR_QUOTED_STRING_sempred(self, localctx, predIndex) -> bool:
     if predIndex == 0:
         return self.tags[0] == self.text
+    return False
 
 
 SqlBaseLexer.tags = []
@@ -46,7 +47,7 @@ class ExceptionErrorListener(ErrorListener):
     """
 
     def syntaxError(self, recognizer, offendingSymbol, line, column, msg, e):
-        raise ParsingException(f'line{line}:{column} {msg}')
+        raise ParsingException(f"line{line}:{column} {msg}")
 
 
 class Statement:
@@ -76,10 +77,7 @@ def query(self) -> str:
         """
         Returns the query, comments and ';' are not included.
         """
-        return self.ctx.parser.getTokenStream().getText(
-            start=self.ctx.start.tokenIndex,
-            stop=self.ctx.stop.tokenIndex
-        )
+        return self.ctx.parser.getTokenStream().getText(start=self.ctx.start.tokenIndex, stop=self.ctx.stop.tokenIndex)
 
     @property
     def type(self):
@@ -96,8 +94,8 @@ def sqlparse(query: str) -> List[Statement]:
     """
     Parses a string into SQL `Statement`.
     """
-    input = CaseInsensitiveStream(query)
-    lexer = SqlBaseLexer(input)
+    input_ = CaseInsensitiveStream(query)
+    lexer = SqlBaseLexer(input_)
     lexer.removeErrorListeners()
     stream = CommonTokenStream(lexer)
 
@@ -109,8 +107,6 @@ def sqlparse(query: str) -> List[Statement]:
 
     # At this point, all errors are already raised; it's seasonably safe to assume
     # that the statements are valid.
-    statements = list(filter(
-        lambda children: isinstance(children, SqlBaseParser.StatementContext), tree.children
-    ))
+    statements = list(filter(lambda children: isinstance(children, SqlBaseParser.StatementContext), tree.children))
 
     return [Statement(statement) for statement in statements]
diff --git a/cratedb_sqlparse_py/pyproject.toml b/cratedb_sqlparse_py/pyproject.toml
index eb56846..c5c6a20 100644
--- a/cratedb_sqlparse_py/pyproject.toml
+++ b/cratedb_sqlparse_py/pyproject.toml
@@ -116,6 +116,12 @@ install_types = true
 ignore_missing_imports = true
 implicit_optional = true
 non_interactive = true
+# FIXME: Does not work?
+exclude = [
+  "^SqlBaseLexer\\.py$",
+  "cratedb_sqlparse/generated_parser/",
+  "cratedb_sqlparse/generated_parser/SqlBaseParser.py",
+]
 
 [tool.pytest.ini_options]
 addopts = """
@@ -197,17 +203,17 @@ check = [
 ]
 
 format = [
-  # { cmd = "ruff format ." },
+  { cmd = "ruff format ." },
   # Configure Ruff not to auto-fix (remove!) unused variables (F841) and `print` statements (T201).
-  # { cmd = "ruff check --fix --ignore=ERA --ignore=F401 --ignore=F841 --ignore=T20 ." },
+  { cmd = "ruff check --fix --ignore=ERA --ignore=F401 --ignore=F841 --ignore=T20 ." },
   { cmd = "pyproject-fmt --keep-full-version pyproject.toml" },
 ]
 
 lint = [
-  # { cmd = "ruff format --check ." },
-  # { cmd = "ruff check ." },
+  { cmd = "ruff format --check ." },
+  { cmd = "ruff check ." },
   { cmd = "validate-pyproject pyproject.toml" },
-  # { cmd = "mypy" },
+  # { cmd = "mypy ." },
 ]
 
 release = [
diff --git a/cratedb_sqlparse_py/tests/conftest.py b/cratedb_sqlparse_py/tests/conftest.py
index 3d5d40f..fcddbce 100644
--- a/cratedb_sqlparse_py/tests/conftest.py
+++ b/cratedb_sqlparse_py/tests/conftest.py
@@ -1,10 +1,10 @@
 import subprocess
 import sys
+from importlib.util import find_spec
 from pathlib import Path
 
 import pytest
 
-
 HERE = Path(__file__).parent
 PROJECT_ROOT = HERE.parent.parent
 SETUP_GRAMMAR = PROJECT_ROOT / "setup_grammar.py"
@@ -16,11 +16,13 @@ def generate():
     Pytest fixture to generate runtime grammar from grammar description.
     """
     try:
-        import cratedb_sqlparse.generated_parser.SqlBaseParser
+        # Test module for availability.
+        find_spec("cratedb_sqlparse.generated_parser.SqlBaseParser")
     except ImportError:
-        subprocess.check_call([sys.executable, SETUP_GRAMMAR], cwd=HERE.parent.parent)
+        subprocess.check_call([sys.executable, SETUP_GRAMMAR], cwd=HERE.parent.parent)  # noqa: S603
 
     try:
-        import cratedb_sqlparse.generated_parser.SqlBaseParser
-    except ImportError:
-        raise RuntimeError("Python grammar has not been generated")
+        # Test module for availability.
+        find_spec("cratedb_sqlparse.generated_parser.SqlBaseParser")
+    except ImportError as ex:
+        raise RuntimeError("Python grammar has not been generated") from ex
diff --git a/cratedb_sqlparse_py/tests/test_lexer.py b/cratedb_sqlparse_py/tests/test_lexer.py
index 427df73..a69588e 100644
--- a/cratedb_sqlparse_py/tests/test_lexer.py
+++ b/cratedb_sqlparse_py/tests/test_lexer.py
@@ -3,20 +3,22 @@
 
 def test_sqlparser_one_statement(query=None):
     from cratedb_sqlparse import sqlparse
-    query = query or 'SELECT 1;'
+
+    query = query or "SELECT 1;"
     r = sqlparse(query)
 
     assert len(r) == 1
 
     stmt = r[0]
 
-    assert stmt.query == query.replace(';', '')  # obj.query doesn't include comments or ';'
+    assert stmt.query == query.replace(";", "")  # obj.query doesn't include comments or ';'
     assert stmt.original_query == query
-    assert stmt.type == 'SELECT'
+    assert stmt.type == "SELECT"
 
 
 def test_sqlparse_several_statements():
     from cratedb_sqlparse import sqlparse
+
     query = """
     SELECT 1;
     INSERT INTO doc.tbl VALUES (1,2,3,4,5,6);
@@ -29,12 +31,13 @@ def test_sqlparse_several_statements():
 
     test_sqlparser_one_statement(r[0].query)
 
-    assert r[1].type == 'INSERT'
-    assert r[2].type == 'SELECT'
+    assert r[1].type == "INSERT"
+    assert r[2].type == "SELECT"
 
 
 def test_sqlparse_dollar_string():
     from cratedb_sqlparse import sqlparse
+
     query = "update test set a=$$test;test$$"
     r = sqlparse(query)
 
@@ -42,7 +45,8 @@ def test_sqlparse_dollar_string():
 
 
 def test_sqlparse_raises_exception():
-    from cratedb_sqlparse import sqlparse, ParsingException
+    from cratedb_sqlparse import ParsingException, sqlparse
+
     query = "SALUT MON AMIE"
 
     with pytest.raises(ParsingException):
@@ -51,6 +55,7 @@ def test_sqlparse_raises_exception():
 
 def test_sqlparse_is_case_insensitive():
     from cratedb_sqlparse import sqlparse
+
     query = "inSerT InTo doc.Tbl1 Values (1)"
 
     r = sqlparse(query)