Added checker for multiline list comprehensions ban (#48)

README.md

@@ -40,6 +40,8 @@ PyLint with checks for common mistakes and issues in Python code specifically in
     * [`C8915`: `spark-outside-function`](#c8915-spark-outside-function)
     * [`C8917`: `use-display-instead-of-show`](#c8917-use-display-instead-of-show)
     * [`W8916`: `no-spark-argument-in-function`](#w8916-no-spark-argument-in-function)
+  * [`readability` checker](#readability-checker)
+    * [`R8923`: `rewrite-as-for-loop`](#r8923-rewrite-as-for-loop)
   * [`mocking` checker](#mocking-checker)
     * [`R8918`: `explicit-dependency-required`](#r8918-explicit-dependency-required)
     * [`R8919`: `obscure-mock`](#r8919-obscure-mock)
@@ -295,6 +297,21 @@ To disable this check on a specific line, add `# pylint: disable=no-spark-argume
 
 [[back to top](#pylint-plugin-for-databricks)]
 
+## `readability` checker
+To use this checker, add `databricks.labs.pylint.readability` to `load-plugins` configuration in your `pylintrc` or `pyproject.toml` file.
+
+[[back to top](#pylint-plugin-for-databricks)]
+
+### `R8923`: `rewrite-as-for-loop`
+
+List comprehension spans multiple lines, rewrite as for loop. List comprehensions in Python are typically used to create new lists by iterating over an existing
+            iterable in a concise, one-line syntax. However, when a list comprehension becomes too complex or spans 
+            multiple lines, it may lose its readability and clarity, which are key advantages of Python's syntax.
+
+To disable this check on a specific line, add `# pylint: disable=rewrite-as-for-loop` at the end of it.
+
+[[back to top](#pylint-plugin-for-databricks)]
+
 ## `mocking` checker
 To use this checker, add `databricks.labs.pylint.mocking` to `load-plugins` configuration in your `pylintrc` or `pyproject.toml` file.
 
@@ -372,7 +389,7 @@ To disable this check on a specific line, add `# pylint: disable=dead-code` at t
 To test this plugin in isolation, you can use the following command:
 
 ```bash
-pylint --load-plugins=databricks.labs.pylint.all --disable=all --enable=missing-data-security-mode,unsupported-runtime,dbutils-fs-cp,dbutils-fs-head,dbutils-fs-ls,dbutils-fs-mount,dbutils-credentials,dbutils-notebook-run,pat-token-leaked,internal-api,legacy-cli,incompatible-with-uc,notebooks-too-many-cells,notebooks-percent-run,spark-outside-function,use-display-instead-of-show,no-spark-argument-in-function,explicit-dependency-required,obscure-mock,mock-no-assign,mock-no-usage,dead-code .
+pylint --load-plugins=databricks.labs.pylint.all --disable=all --enable=missing-data-security-mode,unsupported-runtime,dbutils-fs-cp,dbutils-fs-head,dbutils-fs-ls,dbutils-fs-mount,dbutils-credentials,dbutils-notebook-run,pat-token-leaked,internal-api,legacy-cli,incompatible-with-uc,notebooks-too-many-cells,notebooks-percent-run,spark-outside-function,use-display-instead-of-show,no-spark-argument-in-function,rewrite-as-for-loop,explicit-dependency-required,obscure-mock,mock-no-assign,mock-no-usage,dead-code .
 ```
 
 [[back to top](#pylint-plugin-for-databricks)]

scripts/docs.py

@@ -9,6 +9,7 @@
 from databricks.labs.pylint.legacy import LegacyChecker
 from databricks.labs.pylint.mocking import MockingChecker
 from databricks.labs.pylint.notebooks import NotebookChecker
+from databricks.labs.pylint.readability import ReadabilityChecker
 from databricks.labs.pylint.spark import SparkChecker
 
 
@@ -23,6 +24,7 @@ def do_something():
         LegacyChecker(linter),
         NotebookChecker(linter),
         SparkChecker(linter),
+        ReadabilityChecker(linter),
         MockingChecker(linter),
         EradicateChecker(linter),
     ]:

src/databricks/labs/pylint/all.py

@@ -4,6 +4,7 @@
 from databricks.labs.pylint.legacy import LegacyChecker
 from databricks.labs.pylint.mocking import MockingChecker
 from databricks.labs.pylint.notebooks import NotebookChecker
+from databricks.labs.pylint.readability import ReadabilityChecker
 from databricks.labs.pylint.spark import SparkChecker
 
 
@@ -15,3 +16,4 @@ def register(linter):
     linter.register_checker(SparkChecker(linter))
     linter.register_checker(MockingChecker(linter))
     linter.register_checker(EradicateChecker(linter))
+    linter.register_checker(ReadabilityChecker(linter))

src/databricks/labs/pylint/readability.py

@@ -0,0 +1,23 @@
+from astroid import nodes  # type: ignore
+from pylint.checkers import BaseChecker
+
+
+class ReadabilityChecker(BaseChecker):
+    name = "readability"
+    msgs = {
+        "R8923": (
+            "List comprehension spans multiple lines, rewrite as for loop",
+            "rewrite-as-for-loop",
+            """List comprehensions in Python are typically used to create new lists by iterating over an existing
+            iterable in a concise, one-line syntax. However, when a list comprehension becomes too complex or spans 
+            multiple lines, it may lose its readability and clarity, which are key advantages of Python's syntax.""",
+        ),
+    }
+
+    def visit_listcomp(self, node: nodes.ListComp) -> None:
+        if node.lineno != node.end_lineno:
+            self.add_message("rewrite-as-for-loop", node=node)
+
+
+def register(linter):
+    linter.register_checker(ReadabilityChecker(linter))

tests/test_readability.py

@@ -0,0 +1,16 @@
+from databricks.labs.pylint.readability import ReadabilityChecker
+
+
+def test_single_line_list_comprehensions_allowed(lint_with):
+    messages = lint_with(ReadabilityChecker) << """[x for x in range(10) if x % 2 == 0]"""
+    assert not messages
+
+
+def test_multi_line_list_comprehensions_not_allowed(lint_with):
+    messages = (
+        lint_with(ReadabilityChecker)
+        << """[
+        x for x in range(10) if x % 2 == 0
+    ]"""
+    )
+    assert messages == {"[rewrite-as-for-loop] List comprehension spans multiple lines, rewrite as for loop"}