Add mypy python linter

.github/workflows/test.yml

@@ -67,6 +67,8 @@ jobs:
           pip install -r ./requirements.txt
           cd ../flake8/
           pip install -r ./requirements.txt
+          cd ../mypy/
+          pip install -r ./requirements.txt
 
       # Ruby
 

README.md

@@ -27,6 +27,7 @@
 - **Python:**
   - [Black](https://black.readthedocs.io)
   - [Flake8](http://flake8.pycqa.org)
+  - [Mypy](https://mypy.readthedocs.io/)
 - **Ruby:**
   - [RuboCop](https://rubocop.readthedocs.io)
 - **Swift:**
@@ -137,7 +138,7 @@ jobs:
 
 ### Linter-specific options
 
-`[linter]` can be one of `black`, `eslint`, `flake8`, `gofmt`, `golint`, `prettier`, `rubocop`, `stylelint`, `swiftformat` and `swiftlint`:
+`[linter]` can be one of `black`, `eslint`, `flake8`, `gofmt`, `golint`, `mypy`, `prettier`, `rubocop`, `stylelint`, `swiftformat` and `swiftlint`:
 
 - **`[linter]`:** Enables the linter in your repository. Default: `false`
 - **`[linter]_args`**: Additional arguments to pass to the linter. Example: `eslint_args: "--max-warnings 0"` if ESLint checks should fail even if there are no errors and only warnings. Default: `""`

action.yml

@@ -132,6 +132,22 @@ inputs:
     required: false
     default: "py"
 
+  mypy:
+    description: Enable or disable mypy checks
+    required: false
+    default: false
+  mypy_args:
+    description: Additional arguments to pass to the linter
+    required: false
+    default: ""
+  mypy_dir:
+    description: Directory where the mypy command should be run
+    required: false
+  mypy_extensions:
+    description: Extensions of files to check with mypy
+    required: false
+    default: "py"
+
   # Ruby
 
   rubocop:

src/linters/index.js

@@ -3,6 +3,7 @@ const ESLint = require("./eslint");
 const Flake8 = require("./flake8");
 const Gofmt = require("./gofmt");
 const Golint = require("./golint");
+const Mypy = require("./mypy");
 const Prettier = require("./prettier");
 const RuboCop = require("./rubocop");
 const Stylelint = require("./stylelint");
@@ -14,6 +15,7 @@ const linters = {
 	eslint: ESLint,
 	flake8: Flake8,
 	golint: Golint,
+	mypy: Mypy,
 	rubocop: RuboCop,
 	stylelint: Stylelint,
 	swiftlint: SwiftLint,

src/linters/mypy.js

@@ -0,0 +1,102 @@
+const fs = require("fs");
+const { sep } = require("path");
+
+const commandExists = require("../../vendor/command-exists");
+const { log, run } = require("../utils/action");
+const { initLintResult } = require("../utils/lint-result");
+
+const PARSE_REGEX = /^(.*):([0-9]+): (\w*): (.*)$/gm;
+
+/**
+ * https://mypy.readthedocs.io/en/stable/
+ */
+class Mypy {
+	static get name() {
+		return "Mypy";
+	}
+
+	/**
+	 * Verifies that all required programs are installed. Throws an error if programs are missing
+	 * @param {string} dir - Directory to run the linting program in
+	 */
+	static async verifySetup(dir) {
+		// Verify that Python is installed (required to execute Flake8)
+		if (!(await commandExists("python"))) {
+			throw new Error("Python is not installed");
+		}
+
+		// Verify that mypy is installed
+		if (!(await commandExists("mypy"))) {
+			throw new Error(`${this.name} is not installed`);
+		}
+	}
+
+	/**
+	 * Runs the linting program and returns the command output
+	 * @param {string} dir - Directory to run the linter in
+	 * @param {string[]} extensions - File extensions which should be linted
+	 * @param {string} args - Additional arguments to pass to the linter
+	 * @param {boolean} fix - Whether the linter should attempt to fix code style issues automatically
+	 * @returns {{status: number, stdout: string, stderr: string}} - Output of the lint command
+	 */
+	static lint(dir, extensions, args = "", fix = false) {
+		if (fix) {
+			log(`${this.name} does not support auto-fixing`, "warning");
+		}
+
+		let specifiedPath = false;
+		// Check if they passed a directory as an arg
+		for (const arg of args.split(" ")) {
+			if (fs.existsSync(arg)) {
+				specifiedPath = true;
+				break;
+			}
+		}
+		let extraArgs = "";
+		if (!specifiedPath) {
+			extraArgs = ` ${dir}`;
+		}
+		return run(`mypy ${args}${extraArgs}`, {
+			dir,
+			ignoreErrors: true,
+		});
+	}
+
+	/**
+	 * Parses the output of the lint command. Determines the success of the lint process and the
+	 * severity of the identified code style violations
+	 * @param {string} dir - Directory in which the linter has been run
+	 * @param {{status: number, stdout: string, stderr: string}} output - Output of the lint command
+	 * @returns {{isSuccess: boolean, warning: [], error: []}} - Parsed lint result
+	 */
+	static parseOutput(dir, output) {
+		const lintResult = initLintResult();
+		lintResult.isSuccess = output.status === 0;
+
+		const matches = output.stdout.matchAll(PARSE_REGEX);
+		for (const match of matches) {
+			const [_, pathFull, line, level, text] = match;
+			const leadingSep = `.${sep}`;
+			let path = pathFull;
+			if (path.startsWith(leadingSep)) {
+				path = path.substring(2); // Remove "./" or ".\" from start of path
+			}
+			const lineNr = parseInt(line, 10);
+			const result = {
+				path,
+				firstLine: lineNr,
+				lastLine: lineNr,
+				message: text,
+			};
+			if (level === "error") {
+				lintResult.error.push(result);
+			} else if (level === "warning") {
+				lintResult.warning.push(result);
+			}
+		}
+
+		return lintResult;
+	}
+}
+
+module.exports = Mypy;

test/linters/linters.test.js

@@ -9,6 +9,7 @@ const eslintTypescriptParams = require("./params/eslint-typescript");
 const flake8Params = require("./params/flake8");
 const gofmtParams = require("./params/gofmt");
 const golintParams = require("./params/golint");
+const mypyParams = require("./params/mypy");
 const prettierParams = require("./params/prettier");
 const ruboCopParams = require("./params/rubocop");
 const stylelintParams = require("./params/stylelint");
@@ -22,6 +23,7 @@ const linterParams = [
 	flake8Params,
 	gofmtParams,
 	golintParams,
+	mypyParams,
 	prettierParams,
 	ruboCopParams,
 	stylelintParams,

test/linters/params/mypy.js

@@ -0,0 +1,45 @@
+const { EOL } = require("os");
+
+const Mypy = require("../../../src/linters/mypy");
+
+const testName = "mypy";
+const linter = Mypy;
+const extensions = ["py"];
+
+// Linting without auto-fixing
+function getLintParams(dir) {
+	const stdoutPart1 = `file1.py:7: error: Dict entry 0 has incompatible type "str": "int"; expected "str": "str"`;
+	const stdoutPart2 = `file1.py:11: error: Argument 1 to "main" has incompatible type "List[str]"; expected "str"`;
+	return {
+		// Expected output of the linting function
+		cmdOutput: {
+			status: 1,
+			stdoutParts: [stdoutPart1, stdoutPart2],
+			stdout: `${stdoutPart1}${EOL}${stdoutPart2}`,
+		},
+		// Expected output of the parsing function
+		lintResult: {
+			isSuccess: false,
+			warning: [],
+			error: [
+				{
+					path: "file1.py",
+					firstLine: 7,
+					lastLine: 7,
+					message: `Dict entry 0 has incompatible type "str": "int"; expected "str": "str"`,
+				},
+				{
+					path: "file1.py",
+					firstLine: 11,
+					lastLine: 11,
+					message: `Argument 1 to "main" has incompatible type "List[str]"; expected "str"`,
+				},
+			],
+		},
+	};
+}
+
+// Linting with auto-fixing
+const getFixParams = getLintParams; // Does not support auto-fixing -> option has no effect
+
+module.exports = [testName, linter, extensions, getLintParams, getFixParams];

test/linters/projects/mypy/file1.py

@@ -0,0 +1,11 @@
+from file2 import helper
+
+
+def main(input_str: str):
+    print(input_str)
+    print(helper({
+        input_str: 42,
+    }))
+
+
+main(["hello"])

test/linters/projects/mypy/file2.py

@@ -0,0 +1,5 @@
+from typing import Mapping
+
+
+def helper(var: Mapping[str, str]):
+    pass

test/linters/projects/mypy/requirements.txt

@@ -0,0 +1 @@
+mypy>=0.761