Add Bitcoin vs Global M2 chart

tests/test_bitcoin_m2.py

@@ -0,0 +1,57 @@
+import matplotlib
+
+matplotlib.use("Agg")
+
+import os
+import sys
+import pandas as pd
+
+sys.path.append(os.path.abspath("."))
+
+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)
+    return btc, m2
+
+
+def test_plot_bitcoin_m2_returns_figure():
+    btc, m2 = sample_data()
+    fig = plot_bitcoin_m2(btc, m2, 94, 1)
+    assert len(fig.axes) == 2
+    assert any(ax.get_lines() for ax in fig.axes)
+
+
+def test_btc_m2_main(monkeypatch):
+    btc, m2 = sample_data()
+
+    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"])
+    assert len(fig.axes) == 2
+
+
+def test_btc_m2_main_saves_output(tmp_path, monkeypatch):
+    btc, m2 = sample_data()
+
+    def fake_fetch(*_args, **_kwargs):
+        return btc, m2
+
+    monkeypatch.setattr("scripts.bitcoin_m2_chart.fetch_series", fake_fetch)
+    out_file = tmp_path / "out.png"
+    btc_m2_main(
+        [
+            "--btc-series",
+            "BTC",
+            "--m2-series",
+            "M2",
+            "--output",
+            str(out_file),
+        ]
+    )
+    assert out_file.exists()