[test][test_plotter] Code cleanup

beat/core/test/test_plotter.py

@@ -36,9 +36,6 @@
 
 import imghdr
 
-import numpy
-import six
-
 import nose.tools
 
 from ..plotter import Plotter
@@ -49,22 +46,22 @@ from . import prefix
 def test_default():
 
     p = Plotter(prefix, data=None)
-    assert not p.valid
+    nose.tools.assert_false(p.valid)
 
 
 def test_scatter():
 
     p = Plotter(prefix, "user/scatter/1")
-    assert p.valid, "\n  * %s" % "\n  * ".join(p.errors)
+    nose.tools.assert_true(p.valid, "\n  * %s" % "\n  * ".join(p.errors))
 
 
 def do_plot(mimetype):
 
     p = Plotter(prefix, "user/scatter/1")
-    assert p.valid
+    nose.tools.assert_true(p.valid)
 
     runnable = p.runner()
-    assert runnable.ready is False
+    nose.tools.assert_false(runnable.ready)
     runnable.setup(
         {
             "xlabel": "Temperature in C",
@@ -73,7 +70,7 @@ def do_plot(mimetype):
             "mimetype": mimetype,
         }
     )
-    assert runnable.ready
+    nose.tools.assert_true(runnable.ready)
 
     # now produce the plot
     data = p.dataformat.type(
@@ -111,18 +108,14 @@ def test_plot_jpeg():
 
 def test_plot_pdf():
     fig = do_plot("application/pdf")
-
-    if six.PY2:
-        assert fig.startswith("%PDF")
-    else:
-        assert fig.startswith(b"%PDF")
+    nose.tools.assert_true(fig.startswith(b"%PDF"))
     # with open('test.pdf', 'wb') as f: f.write(fig)
 
 
 def test_plot_many_lines():
 
     p = Plotter(prefix, "user/scatter/1")
-    assert p.valid
+    nose.tools.assert_true(p.valid)
 
     data1 = p.dataformat.type(
         data=[
@@ -157,7 +150,7 @@ def test_plot_many_lines():
     )
 
     runnable = p.runner()
-    assert runnable.ready is False
+    nose.tools.assert_false(runnable.ready)
     runnable.setup(
         {
             "title": "Test plot",
@@ -169,7 +162,7 @@ def test_plot_many_lines():
             "mimetype": "image/png",
         }
     )
-    assert runnable.ready
+    nose.tools.assert_true(runnable.ready)
 
     fig = runnable.process([data1, data2])
     nose.tools.eq_(imghdr.what("test.png", fig), "png")