Added ImageExporter test for py2-pyside fix

pyqtgraph/exporters/tests/test_image.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+import pyqtgraph as pg
+from pyqtgraph.exporters import ImageExporter
+
+app = pg.mkQApp()
+
+
+def test_ImageExporter_filename_dialog():
+    """Tests ImageExporter code path that opens a file dialog. Regression test
+    for pull request 1133."""
+    p = pg.plot()
+    exp = ImageExporter(p.getPlotItem())
+    exp.export()