plotter: show appropriate error when plotting a dataframe but column was not specified

When you try to plot a dataframe without specifying the column, the code
that checks it fails with

KeyError: "column"

Fix the check so that the appropriate error (ValueError: Column not
specified for DataFrame input) is printed.

1 files changed, 4 insertions, 0 deletions

diff --git a/tests/test_plotter.py b/tests/test_plotter.py
index a2a17f5..e2d622a 100644
--- a/tests/test_plotter.py
+++ b/tests/test_plotter.py
@@ -249,11 +249,15 @@ class TestPlotter(BaseTestThermal):
 
 class TestILinePlotter(unittest.TestCase):
     def test_simple_dfr(self):
+        """ILinePlot doesn't barf when plotting DataFrames"""
         dfr1 = pd.DataFrame([1, 2, 3, 4], columns=["a"])
         dfr2 = pd.DataFrame([2, 3, 4, 5], columns=["a"])
 
         trappy.ILinePlot([dfr1, dfr2], column=["a", "a"]).view(test=True)
 
+        with self.assertRaises(ValueError):
+            trappy.ILinePlot([dfr1, dfr2]).view(test=True)
+
     def test_duplicate_merging(self):
         dfr1 = pd.DataFrame([1, 2, 3, 4], index=[0., 0., 1., 2.], columns=["a"])
         dfr2 = pd.DataFrame([2, 3, 4, 5], index=[1., 1., 1., 2.], columns=["a"])