Merge pull request #38 from dopplershift/set-backend

ENH: Support setting the backend per-test. (Fixes #35)

Author: astrofrog

.travis.yml

@@ -13,10 +13,7 @@ env:
     - CONDA_DEPENDENCIES="pytest matplotlib nose coverage"
     - PIP_DEPENDENCIES="pytest-cov coveralls"
   matrix:
-    - PYTHON_VERSION=2.6 MATPLOTLIB_VERSION=1.4 NUMPY_VERSION=1.9
-    - PYTHON_VERSION=2.7 MATPLOTLIB_VERSION=1.4 NUMPY_VERSION=1.9
-    - PYTHON_VERSION=3.3 MATPLOTLIB_VERSION=1.4 NUMPY_VERSION=1.9
-    - PYTHON_VERSION=3.4 MATPLOTLIB_VERSION=1.4 NUMPY_VERSION=1.9
+    - PYTHON_VERSION=3.4 MATPLOTLIB_VERSION=1.5
     - PYTHON_VERSION=2.7 MATPLOTLIB_VERSION=1.5
     - PYTHON_VERSION=3.5 MATPLOTLIB_VERSION=1.5
     - PYTHON_VERSION=2.7 MATPLOTLIB_VERSION=2.0
@@ -40,7 +37,7 @@ install:
 script:
    - python -c 'import pytest_mpl.plugin'
    - py.test --mpl --cov pytest_mpl tests
-   - if [[ $PYTHON_VERSION != 2.6 ]]; then python setup.py check --restructuredtext; fi
+   - python setup.py check --restructuredtext
 
 after_success:
    - coveralls

appveyor.yml

@@ -13,15 +13,9 @@ environment:
       CONDA_DEPENDENCIES: "pytest matplotlib nose"
 
   matrix:
-      - PYTHON_VERSION: "2.6"
-        MATPLOTLIB_VERSION: "1.4"
-
       - PYTHON_VERSION: "2.7"
         MATPLOTLIB_VERSION: "1.5"
 
-      - PYTHON_VERSION: "3.3"
-        MATPLOTLIB_VERSION: "1.5"
-
       - PYTHON_VERSION: "3.4"
         MATPLOTLIB_VERSION: "1.5"
 

pytest_mpl/plugin.py

@@ -30,6 +30,7 @@
 
 from functools import wraps
 
+import contextlib
 import os
 import sys
 import shutil
@@ -95,6 +96,19 @@ def pytest_configure(config):
                                                       results_dir=results_dir))
 
 
+@contextlib.contextmanager
+def switch_backend(backend):
+    import matplotlib
+    import matplotlib.pyplot as plt
+    prev_backend = matplotlib.get_backend().lower()
+    if prev_backend != backend.lower():
+        plt.switch_backend(backend)
+        yield
+        plt.switch_backend(prev_backend)
+    else:
+        yield
+
+
 class ImageComparison(object):
 
     def __init__(self, config, baseline_dir=None, generate_dir=None, results_dir=None):
@@ -123,6 +137,7 @@ def pytest_runtest_setup(self, item):
         savefig_kwargs = compare.kwargs.get('savefig_kwargs', {})
         style = compare.kwargs.get('style', 'classic')
         remove_text = compare.kwargs.get('remove_text', False)
+        backend = compare.kwargs.get('backend', 'agg')
 
         if MPL_LT_15 and style == 'classic':
             style = os.path.join(os.path.dirname(__file__), 'classic.mplstyle')
@@ -144,7 +159,7 @@ def item_function_wrapper(*args, **kwargs):
 
             baseline_remote = baseline_dir.startswith('http')
 
-            with plt.style.context(style):
+            with plt.style.context(style), switch_backend(backend):
 
                 # Run test and get figure object
                 import inspect