Add minimal test of last shared function

dp_wizard/utils/shared.py

@@ -61,9 +61,7 @@ def df_to_columns(df: DataFrame):
     return transposed if transposed else (tuple(), tuple())
 
 
-def plot_bars(
-    df: DataFrame, error: float, cutoff: float, title: str
-):  # pragma: no cover
+def plot_bars(df: DataFrame, error: float, cutoff: float, title: str):
     """
     Given a Dataframe, make a bar plot of the data in the last column,
     with labels from the prior columns.

tests/utils/test_code_generators.py

@@ -204,6 +204,9 @@ def id_for_plan(plan: AnalysisPlan):
 @pytest.mark.parametrize("plan", plans, ids=id_for_plan)
 def test_make_notebook(plan):
     notebook = NotebookGenerator(plan).make_py()
+
+    assert "no cover" not in notebook
+
     print(number_lines(notebook))
     globals = {}
     exec(notebook, globals)
@@ -219,6 +222,8 @@ def test_make_script(plan):
     assert "# -" not in script
     assert "# +" not in script
 
+    assert "no cover" not in script
+
     with NamedTemporaryFile(mode="w") as fp:
         fp.write(script)
         fp.flush()

tests/utils/test_shared.py

@@ -1,4 +1,4 @@
-from dp_wizard.utils.shared import df_to_columns
+from dp_wizard.utils.shared import df_to_columns, plot_bars
 import polars as pl
 
 
@@ -55,3 +55,22 @@ def test_no_rows_df_to_columns():
         tuple(),
         tuple(),
     )
+
+
+def test_plot_bars():
+    # TODO: This test should be stronger, but wait until we move to plotly.
+    # https://github.com/opendp/dp-wizard/issues/552
+    plot_bars(
+        df=pl.DataFrame(
+            {
+                "x": ["a", "b", "c"],
+                "y": [0, 20, 10],
+            }
+        ),
+        error=10,
+        cutoff=0,
+        title="Testing 123",
+    )
+    import matplotlib.pyplot as plt
+
+    plt.close()