Drop NaN rows before validation

tests/test_bitcoin_m2.py

@@ -12,15 +12,25 @@ from scripts.bitcoin_m2_chart import plot_bitcoin_m2, main as btc_m2_main
 
 
 def sample_data():
-    dates = pd.date_range("2021-01-01", periods=5, freq="D")
-    btc = pd.DataFrame({"value": [10, 11, 12, 13, 14]}, index=dates)
-    m2 = pd.DataFrame({"value": [1, 2, 3, 4, 5]}, index=dates)
+    btc_dates = pd.date_range("2024-07-01", periods=10, freq="D")
+    btc = pd.DataFrame({"value": range(10, 20)}, index=btc_dates)
+    m2_dates = btc_dates
+    m2 = pd.DataFrame({"value": range(1, 11)}, index=m2_dates)
+    return btc, m2
+
+
+def sample_data_with_nan():
+    btc_dates = pd.date_range("2024-07-01", periods=10, freq="D")
+    btc = pd.DataFrame({"value": range(10, 20)}, index=btc_dates)
+    m2_dates = btc_dates
+    m2_values = list(range(1, 10)) + [pd.NA]
+    m2 = pd.DataFrame({"value": m2_values}, index=m2_dates)
     return btc, m2
 
 
 def test_plot_bitcoin_m2_returns_figure():
     btc, m2 = sample_data()
-    fig = plot_bitcoin_m2(btc, m2, 94, 1)
+    fig = plot_bitcoin_m2(btc, m2, 0, 1)
     assert len(fig.axes) == 2
     assert any(ax.get_lines() for ax in fig.axes)
 
@@ -32,19 +42,44 @@ def test_btc_m2_main(monkeypatch):
         return btc, m2
 
     monkeypatch.setattr("scripts.bitcoin_m2_chart.fetch_series", fake_fetch)
-    fig = btc_m2_main([
-        "--btc-series",
-        "BTC",
-        "--m2-series",
-        "M2",
-        "--width",
-        "8",
-        "--height",
-        "4",
-        "--dpi",
-        "150",
-        "--no-show",
-    ])
+    fig = btc_m2_main(
+        [
+            "--btc-series",
+            "BTC",
+            "--m2-series",
+            "M2",
+            "--offset",
+            "0",
+            "--width",
+            "8",
+            "--height",
+            "4",
+            "--dpi",
+            "150",
+            "--no-show",
+        ]
+    )
+    assert len(fig.axes) == 2
+
+
+def test_main_handles_trailing_nan(monkeypatch):
+    btc, m2 = sample_data_with_nan()
+
+    def fake_fetch(*_args, **_kwargs):
+        return btc, m2
+
+    monkeypatch.setattr("scripts.bitcoin_m2_chart.fetch_series", fake_fetch)
+    fig = btc_m2_main(
+        [
+            "--btc-series",
+            "BTC",
+            "--m2-series",
+            "M2",
+            "--offset",
+            "0",
+            "--no-show",
+        ]
+    )
     assert len(fig.axes) == 2
 
 
@@ -64,6 +99,8 @@ def test_btc_m2_main_saves_output(tmp_path, monkeypatch):
             "M2",
             "--output",
             str(out_file),
+            "--offset",
+            "0",
             "--width",
             "8",
             "--height",