tests: Add test cases for diagnostic

.travis.yml

@@ -26,6 +26,13 @@ before_install:
       sleep 3;
     fi
 
+before_script:
+  # nltk 3.2.2 dropped support for Python 3.3
+  - >
+    if [[ "$TRAVIS_PYTHON_VERSION" != "3.3" ]]; then
+      python -m nltk.downloader punkt maxent_treebank_pos_tagger averaged_perceptron_tagger
+    fi
+
 install:
   # beheve is a dev dependeny, so not in requirements.txt.
   - pip install behave

tests/server.features/diagnostic.feature

@@ -0,0 +1,7 @@
+Feature: diagnostic module
+  diagnostic is a module of language-server.
+
+  Scenario: Test output_to_diagnostics
+    Given the output with errors by coala
+    When I pass the parameters to output_to_diagnostics
+    Then it should return output in vscode format

tests/server.features/steps/diagnostic_steps.py

@@ -0,0 +1,35 @@
+# -*- coding: UTF-8 -*-
+
+# @mark.steps
+# ----------------------------------------------------------------------------
+# STEPS:
+# ----------------------------------------------------------------------------
+import os
+from behave import given, when, then
+from coala_langserver.diagnostic import output_to_diagnostics
+from coala_langserver.coalashim import run_coala_with_specific_file
+
+
+@given('the output with errors by coala')
+def step_impl(context):
+    context.dir = os.path.abspath(
+        os.path.join(
+            os.path.dirname(os.path.abspath(__file__)),
+            os.pardir,
+            os.pardir,
+            'resources'
+        )
+    )
+    context.path = os.path.join(context.dir, 'unqualified.py')
+
+    context.output = run_coala_with_specific_file(context.dir, context.path)
+
+
+@when('I pass the parameters to output_to_diagnostics')
+def step_impl(context):
+    context.message = output_to_diagnostics(context.output)
+
+
+@then('it should return output in vscode format')
+def step_impl(context):
+    assert len(context.message) is not 0