Add --verbose and --quiet options to compile.scalastyle

This adds new `--verbose` and `--quiet` options to the `compile.scalastyle` goal, which get threaded directly to scalastyle, as requested in issue pantsbuild#1888.

Note: `scalastyle` currently accepts but ignores the `--verbose` option (See: scalastyle/scalastyle#159).  However, I include it anyway for when that issue is eventually fixed.

Testing Done:
$ ./pants test tests/python/pants_test/tasks:scalastyle_integration # Newly added integration test passes
    $ ./pants test tests/python/pants_test:all # Unit tests pass

I'm relying on Travis for the remaining integration tests

Bugs closed: 2172

Reviewed at https://rbcommons.com/s/twitter/r/2799/

examples/src/scala/org/pantsbuild/example/styleissue/BUILD

@@ -0,0 +1,6 @@
+# Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+scala_library(name = 'styleissue',
+  sources = ['StyleIssue.scala'],
+)

examples/src/scala/org/pantsbuild/example/styleissue/StyleIssue.scala

@@ -0,0 +1,8 @@
+// Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
+// Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+package org.pantsbuild.example.hello.styleissue;
+
+// A program designed to deliberately fail a scalastyle check
+	class StyleIssue {
+	}

examples/src/scala/org/pantsbuild/example/styleissue/style.xml

@@ -0,0 +1,3 @@
+<scalastyle>
+ <check level="error" class="org.scalastyle.file.FileTabChecker" enabled="true" />
+</scalastyle>

src/python/pants/backend/jvm/tasks/scalastyle.py

@@ -71,6 +71,10 @@ def register_options(cls, register):
                   '(relative to the repo root) matches any of these regexes.')
     register('--jvm-options', action='append', metavar='<option>...', advanced=True,
              help='Run scalastyle with these extra jvm options.')
+    register('--verbose', action='store_true', default=False,
+             help='Enable verbose scalastyle output.')
+    register('--quiet', action='store_true', default=False,
+             help='Silence scalastyle error messages.')
     cls.register_jvm_tool(register, 'scalastyle')
 
   @classmethod
@@ -126,6 +130,8 @@ def execute(self):
       invalid_targets = [vt.target for vt in invalidation_check.invalid_vts]
 
       scalastyle_config = self.validate_scalastyle_config()
+      scalastyle_verbose = self.get_options().verbose
+      scalastyle_quiet = self.get_options().quiet
       scalastyle_excluder = self.create_file_excluder()
 
       self.context.log.debug('Non synthetic scala targets to be checked:')
@@ -139,11 +145,19 @@ def execute(self):
 
       if scala_sources:
         def call(srcs):
+          def to_java_boolean(x):
+            return str(x).lower()
+
           cp = self.tool_classpath('scalastyle')
+          scalastyle_args = [
+            '-c', scalastyle_config,
+            '-v', to_java_boolean(scalastyle_verbose),
+            '-q', to_java_boolean(scalastyle_quiet),
+            ]
           return self.runjava(classpath=cp,
                               main=self._MAIN,
                               jvm_options=self.get_options().jvm_options,
-                              args=['-c', scalastyle_config] + srcs)
+                              args=scalastyle_args + srcs)
 
         result = Xargs(call).execute(scala_sources)
         if result != 0:

tests/python/pants_test/tasks/test_scalastyle_integration.py

@@ -35,3 +35,22 @@ def test_scalastyle_cached(self):
         # implying there was as a cache hit
         self.assertNotIn('abc_Scalastyle_compile_scalastyle will write to local artifact cache',
             pants_run.stdout_data)
+
+  def test_scalastyle_without_quiet(self):
+    scalastyle_args = [
+      'compile.scalastyle',
+      '--config=examples/src/scala/org/pantsbuild/example/styleissue/style.xml',
+      'examples/src/scala/org/pantsbuild/example/styleissue',
+      ]
+    pants_run = self.run_pants(scalastyle_args)
+    self.assertIn('Found 2 errors', pants_run.stdout_data)
+
+  def test_scalastyle_with_quiet(self):
+    scalastyle_args = [
+      'compile.scalastyle',
+      '--config=examples/src/scala/org/pantsbuild/example/styleissue/style.xml',
+      '--quiet',
+      'examples/src/scala/org/pantsbuild/example/styleissue',
+      ]
+    pants_run = self.run_pants(scalastyle_args)
+    self.assertNotIn('Found 2 errors', pants_run.stdout_data)