KotlinLintBear.py: Add bear wrapping ktlint

Checks for coding standards or semantic problems
in Kotlin files.

Closes coala#2152

.ci/deps.sh

@@ -62,3 +62,8 @@ wget "https://downloads.sourceforge.net/project/astyle/astyle/astyle%203.0.1/ast
 tar -xvzf ~/astyle.tar.gz -C ~/
 make -C ~/astyle/build/gcc
 sudo make install -C ~/astyle/build/gcc
+
+# ktlint installation
+curl -sSLO https://github.com/shyiko/ktlint/releases/download/0.15.0/ktlint
+sudo chmod a+x ktlint
+sudo mv ktlint /usr/local/bin/

bears/kotlin/KotlinLintBear.py

@@ -0,0 +1,26 @@
+from coalib.bearlib.abstractions.Linter import linter
+from dependency_management.requirements.DistributionRequirement import (
+    DistributionRequirement)
+
+
+@linter(executable='ktlint',
+        global_bear=True,
+        output_format='regex',
+        output_regex=r'(?P<line>\d+):(?P<column>\d+): '
+                     r'(?P<message>.+)')
+class KotlinLintBear:
+    """
+    Lints your Kotlin files.
+    Checks for coding standards or semantic problems in Kotlin files.
+    """
+    LANGUAGES = {'kotlin'}
+    REQUIREMENTS = {DistributionRequirement(brew='shyiko/ktlint/ktlint')}
+    AUTHORS = {'The coala developers'}
+    AUTHORS_EMAILS = {'[email protected]'}
+    LICENSE = 'AGPL-3.0'
+    CAN_DETECT = {'Formatting', 'Syntax'}
+    SEE_MORE = 'https://ktlint.github.io'
+
+    @staticmethod
+    def create_arguments(config_file):
+        return ()

tests/kotlin/KotlinLintBearTest.py

@@ -0,0 +1,39 @@
+import os
+import unittest
+from queue import Queue
+
+from coalib.settings.Section import Section
+from bears.kotlin.KotlinLintBear import KotlinLintBear
+from coalib.testing.BearTestHelper import generate_skip_decorator
+
+
+@generate_skip_decorator(KotlinLintBear)
+class KotlinLintBearTest(unittest.TestCase):
+
+    def setUp(self):
+        self.section = Section('Kotlin')
+        self.queue = Queue()
+        self.file_dict = {}
+        self.uut = KotlinLintBear(self.file_dict, self.section, self.queue)
+
+    def set_config_dir(self, directory):
+        test_path = os.path.abspath(os.path.join(
+            os.path.dirname(__file__), directory))
+        self.uut.get_config_dir = lambda *args, **kwargs: test_path
+
+    def test_bad_files(self):
+        self.set_config_dir('bad_files')
+        results = list(self.uut.run_bear_from_section([], {}))
+        self.assertTrue(len(results) > 10)
+
+    def test_good_files(self):
+        self.set_config_dir('good_files')
+        results = list(self.uut.run_bear_from_section([], {}))
+        self.assertTrue(len(results) == 0)
+
+    def test_config_files(self):
+        self.set_config_dir('test_files')
+        results = list(self.uut.run_bear_from_section([], {}))
+        self.assertTrue(len(results) == 1)
+        self.assertEqual(results[0].message,
+                         'File must end with a newline (\\n)')

tests/kotlin/bad_files/bad_import.kt

@@ -0,0 +1,3 @@
+import io.vertx.core.*
+import com.google.inject.*
+import pkg.UnusedClass

tests/kotlin/bad_files/bad_modifier_order.kt

@@ -0,0 +1,6 @@
+abstract internal class A {
+    open protected val v = ""
+    open suspend internal fun f(v: Any): Any = ""
+    lateinit public var lv: String
+    tailrec abstract fun findFixPoint(x: Double = 1.0): Double
+}

tests/kotlin/bad_files/bad_semicolon.kt

@@ -0,0 +1,6 @@
+    package a.b.c;
+    fun main() {
+        fun name() { a(); return b }
+        println(";")
+        println();
+    }

tests/kotlin/bad_files/bad_string_templates.kt

@@ -0,0 +1,2 @@
+val a = "class = ${String::class.toString()}"
+val b = "not ${a}"

tests/kotlin/good_files/good_file.kt

@@ -0,0 +1,6 @@
+fun a() {
+    val x = 5
+    if (x == 0) {
+        println(a)
+    }
+}

tests/kotlin/good_files/good_modifier_order.kt

@@ -0,0 +1,6 @@
+internal abstract class A {
+    protected open val v = ""
+    internal open suspend fun f(v: Any): Any = ""
+    public lateinit var lv: String
+    abstract tailrec fun findFixPoint(x: Double = 1.0): Double
+}

tests/kotlin/good_files/good_string_templates.kt

@@ -0,0 +1,6 @@
+internal abstract class A {
+    protected open val v = ""
+    internal open suspend fun f(v: Any): Any = ""
+    public lateinit var lv: String
+    abstract tailrec fun findFixPoint(x: Double = 1.0): Double
+}

tests/kotlin/test_files/.editorconfig

@@ -0,0 +1,2 @@
+[*.{kt,kts}]
+insert_final_newline=true

tests/kotlin/test_files/good_file.kt

@@ -0,0 +1,6 @@
+fun a() {
+    val x = 5
+    if (x == 0) {
+        println(a)
+    }
+}