Kotlin and general Gradle support. (#745)

test/test_gradle_build_classpath_command.vader

@@ -0,0 +1,42 @@
+Before:
+  call ale#test#SetDirectory('/testplugin/test')
+  runtime ale_linters/kotlin/kotlinc.vim
+  let g:ale_gradle_path = $PATH
+
+After:
+  call ale#test#RestoreDirectory()
+  call ale#linter#Reset()
+  let $PATH = g:ale_gradle_path
+
+Execute(Should return 'gradlew' command if project includes gradle wapper):
+  call ale#test#SetFilename('gradle-test-files/wrapped-project/src/main/kotlin/dummy.kt')
+
+  let g:project_root = '/testplugin/test/gradle-test-files/wrapped-project'
+  let g:gradle_executable = '/testplugin/test/gradle-test-files/wrapped-project/gradlew'
+  let g:gradle_init_path = '/testplugin/autoload/ale/gradle/init.gradle'
+  let g:gradle_options = '-I ' . g:gradle_init_path . ' -q printClasspath'
+
+
+  AssertEqual
+  \ "cd '" . g:project_root . "' && " . g:gradle_executable . " " . g:gradle_options,
+  \ ale#gradle#BuildClasspathCommand(bufnr(''))
+
+Execute(Should return 'gradle' command if project does not include gradle wapper):
+  call ale#test#SetFilename('gradle-test-files/unwrapped-project/src/main/kotlin/dummy.kt')
+  let $PATH .= ':' . g:dir . '/gradle-test-files'
+
+  let g:project_root = '/testplugin/test/gradle-test-files/unwrapped-project'
+  let g:gradle_executable = 'gradle'
+  let g:gradle_init_path = '/testplugin/autoload/ale/gradle/init.gradle'
+  let g:gradle_options = '-I ' . g:gradle_init_path . ' -q printClasspath'
+
+  AssertEqual
+  \ "cd '" . g:project_root . "' && " . g:gradle_executable . " " . g:gradle_options,
+  \ ale#gradle#BuildClasspathCommand(bufnr(''))
+
+Execute(Should return empty string if gradle cannot be executed):
+  call ale#test#SetFilename('gradle-test-files/non-gradle-project/src/main/kotlin/dummy.kt')
+
+  AssertEqual
+  \ '',
+  \ ale#gradle#BuildClasspathCommand(bufnr(''))

test/test_gradle_find_executable.vader

@@ -0,0 +1,31 @@
+Before:
+  call ale#test#SetDirectory('/testplugin/test')
+  runtime ale_linters/kotlin/kotlinc.vim
+  let g:ale_gradle_path = $PATH
+
+After:
+  call ale#test#RestoreDirectory()
+  call ale#linter#Reset()
+  let $PATH = g:ale_gradle_path
+  
+Execute(Should return 'gradlew' if found in parent directory):
+  call ale#test#SetFilename('gradle-test-files/wrapped-project/src/main/kotlin/dummy.kt')
+
+  AssertEqual
+  \ g:dir . '/gradle-test-files/wrapped-project/gradlew',
+  \ ale#gradle#FindExecutable(bufnr(''))
+
+Execute(Should return 'gradle' if 'gradlew' not found in parent directory):
+  call ale#test#SetFilename('gradle-test-files/unwrapped-project/src/main/kotlin/dummy.kt')
+  let $PATH .= ':' . g:dir . '/gradle-test-files'
+  
+  AssertEqual
+  \ 'gradle', 
+  \ ale#gradle#FindExecutable(bufnr(''))
+
+Execute(Should return empty string if 'gradlew' not in parent directory and gradle not in path):
+  call ale#test#SetFilename('gradle-test-files/unwrapped-project/src/main/kotlin/dummy.kt')
+  
+  AssertEqual
+  \ '', 
+  \ ale#gradle#FindExecutable(bufnr(''))

test/test_gradle_find_project_root.vader

@@ -0,0 +1,35 @@
+Before:
+  call ale#test#SetDirectory('/testplugin/test')
+  runtime ale_linters/kotlin/kotlinc.vim
+
+After:
+  call ale#test#RestoreDirectory()
+  call ale#linter#Reset()
+
+Execute(Should return directory for 'gradlew' if found in parent directory):
+  call ale#test#SetFilename('gradle-test-files/wrapped-project/src/main/kotlin/dummy.kt')
+
+  AssertEqual
+  \ g:dir . '/gradle-test-files/wrapped-project',
+  \ ale#gradle#FindProjectRoot(bufnr(''))
+
+Execute(Should return directory for 'settings.gradle' if found in parent directory):
+  call ale#test#SetFilename('gradle-test-files/settings-gradle-project/src/main/kotlin/dummy.kt')
+
+  AssertEqual
+  \ g:dir . '/gradle-test-files/settings-gradle-project',
+  \ ale#gradle#FindProjectRoot(bufnr(''))
+
+Execute(Should return directory for 'build.gradle' if found in parent directory):
+  call ale#test#SetFilename('gradle-test-files/build-gradle-project/src/main/kotlin/dummy.kt')
+
+  AssertEqual
+  \ g:dir . '/gradle-test-files/build-gradle-project',
+  \ ale#gradle#FindProjectRoot(bufnr(''))
+
+Execute(Should return empty string if gradle files are not found in parent directory):
+  call ale#test#SetFilename('gradle-test-files/non-gradle-project/src/main/kotlin/dummy.kt')
+
+  AssertEqual
+  \ '',
+  \ ale#gradle#FindProjectRoot(bufnr(''))