Python

Supported versions

• Python 3.x
• Python 2.x

Language-specific properties

Discover and update the Python-specific properties in Administration > General Settings > Python.

Custom rules

Overview

The Python analyzer parses the source code, creates an abstract syntax tree (AST), and then walks through the entire tree. A coding rule is a visitor that is able to visit nodes from this AST.

As soon as the coding rule visits a node, it can navigate its children and log issues if necessary.

Writing a plugin

Custom rules for Python can be added by writing a SonarQube Plugin and using Python analyzer APIs. Here are the steps to follow:

Create a SonarQube plugin

• Create a standard SonarQube plugin project.
• Attach this plugin to the SonarQube Python analyzer through the pom.xml:
  • Add the dependency to the Python analyzer.
  • Add the following line in the sonar-packaging-maven-plugin configuration. <requirePlugins>python:2.0-SNAPSHOT</requirePlugin>
    
• Implement the following extension points:
  • Plugin
  • RulesDefinition and PythonCustomRuleRepository, which can be implemented by a single class, to declare your custom rules.
• Declare the RulesDefinition as an extension in the Plugin extension point.

Implement a rule

• Create a class that will hold the implementation of the rule, it should:
  • extend PythonVisitorCheck or PythonSubscriptionCheck.
  • define the rule name, key, tags, etc. with Java annotations.
• declare this class in the RulesDefinition.

Example plugin

A sample plugin can be found here: python-custom-rules to help you get started.

Implementation details

Using PythonVisitorCheck

To explore a part of the AST, override a method from PythonVisitorCheck. For example, if you want to explore "if statement" nodes, override the visitIfStatement method that will be called each time an ifStatement node is encountered in the AST.

Using PythonSubscriptionCheck

To explore a part of the AST, override PythonSubscriptionCheck#initialize and call SubscriptionCheck.Context#registerSyntaxNodeConsumer with the Tree#Kind of node you want to visit. For example, if you want to explore "if statement", you should register to the kind Tree#Kind#IF_STATEMENT and then provide a lambda that will consume a SubscriptionContext to act on such nodes.

Create issues

From the check, an issue can be created by calling the SubscriptionContext#addIssue method or a PythonVisitorCheck #addIssue method.

Testing checks

You can use the PythonCheckVerifier#verify method to test custom checks. Don't forget to add the testkit dependency to access this class from your project:

  <dependency>
      <groupId>org.sonarsource.python</groupId>
      <artifactId>python-checks-testkit</artifactId>
      <version>${project.version}</version>
      <scope>test</scope>
  </dependency>

You should end each line having an issue with a comment in the following form:

# Noncompliant {{Message}}

Comment syntax is described here.

Related Pages

• Importing external issues (Pylint, Bandit, Flake8)
• Test coverage and execution (the Coverage tool provided by Ned Batchelder, Nose, pytest)

Issue tracker

Check the issue tracker for this language.