Fix code coverage for ext packages (#576)

Included extension packages in code coverage test.

Author: reyang

.coveragerc

@@ -1,10 +1,14 @@
 [run]
 branch = True
-omit = 
-       *gen/jaeger*
-       *gen/opencensus*
-       opencensus/__init__.py
-       opencensus/common/__init__.py
+omit =
+    # Test cases
+    contrib/*/tests/*
+    # Auto generated files
+    contrib/opencensus-ext-jaeger/opencensus/ext/jaeger/trace_exporter/gen/*
+    contrib/opencensus-ext-ocagent/opencensus/ext/ocagent/trace_exporter/gen/*
+    # Side-effect introduced by namespace packages
+    opencensus/__init__.py
+    opencensus/common/__init__.py
 
 [report]
 fail_under = 100
@@ -14,8 +18,12 @@ exclude_lines =
     pragma: NO COVER
     # Ignore debug-only repr
     def __repr__
-omit = 
-       *gen/jaeger*
-       *gen/opencensus*
-       opencensus/__init__.py
-       opencensus/common/__init__.py
+omit =
+    # Side-effect introduced by namespace packages
+    contrib/*/opencensus/__init__.py
+    contrib/*/opencensus/ext/__init__.py
+    opencensus/__init__.py
+    opencensus/common/__init__.py
+    # Auto generated files
+    contrib/opencensus-ext-jaeger/opencensus/ext/jaeger/trace_exporter/gen/*
+    contrib/opencensus-ext-ocagent/opencensus/ext/ocagent/trace_exporter/gen/*

nox.py

@@ -61,13 +61,12 @@ def unit(session, py):
     session.run(
         'py.test',
         '--quiet',
-        '--cov=opencensus',
+        '--cov=opencensus', '--cov=contrib',
         '--cov-append',
         '--cov-config=.coveragerc',
         '--cov-report=',
         '--cov-fail-under=97',
-        'tests/unit/',
-        'contrib/',
+        'tests/unit/', 'contrib/',
         *session.posargs
     )