diff --git a/postreise/plot/tests/test_plot_sim_vs_hist.py b/postreise/plot/tests/test_plot_sim_vs_hist.py
new file mode 100644
index 000000000..1bd1c7b6d
--- /dev/null
+++ b/postreise/plot/tests/test_plot_sim_vs_hist.py
@@ -0,0 +1,78 @@
+import pandas as pd
+import pytest
+from powersimdata.tests.mock_scenario import MockScenario
+
+from postreise.plot.plot_sim_vs_hist import plot_generation_sim_vs_hist
+
+mock_plant = {
+    "plant_id": ["A", "B", "C", "D", "E", "F", "G", "H"],
+    "zone_id": [301, 302, 303, 304, 305, 306, 307, 308],
+    "Pmax": [100, 75, 150, 30, 50, 300, 200, 80],
+    "Pmin": [0, 0, 0, 0, 0, 100, 10, 0],
+    "type": ["solar", "wind", "hydro", "hydro", "wind", "coal", "ng", "wind"],
+    "zone_name": [
+        "Far West",
+        "North",
+        "West",
+        "South",
+        "North Central",
+        "South Central",
+        "Coast",
+        "East",
+    ],
+}
+
+mock_pg = pd.DataFrame(
+    {
+        "A": [80, 75, 72, 81],
+        "B": [22, 22, 25, 20],
+        "C": [130, 130, 130, 130],
+        "D": [25, 26, 27, 28],
+        "E": [10, 11, 9, 12],
+        "F": [290, 295, 295, 294],
+        "G": [190, 190, 191, 190],
+        "H": [61, 63, 65, 67],
+    },
+    index=pd.date_range(start="2016-01-01", periods=4, freq="H"),
+)
+
+grid_attrs = {"plant": mock_plant}
+scenario = MockScenario(grid_attrs, pg=mock_pg)
+scenario.info["interconnect"] = "Texas"
+scenario.info["start_date"] = pd.Timestamp(2016, 1, 1)
+scenario.info["end_date"] = pd.Timestamp(2016, 1, 1, 3)
+scenario.state.grid.id2zone = {
+    k: v for k, v in zip(mock_plant["zone_id"], mock_plant["zone_name"])
+}
+scenario.state.grid.zone2id = {v: k for k, v in scenario.state.grid.id2zone.items()}
+scenario.state.grid.model = "usa_tamu"
+
+hist_gen = pd.DataFrame(
+    {
+        "solar": 100 * 4,
+        "wind": 205 * 4,
+        "hydro": 180 * 4,
+        "coal": 300 * 4,
+        "ng": 200 * 4,
+    },
+    index=["Texas"],
+)
+
+
+def test_plot_generation_sim_vs_hist_argument_type():
+    with pytest.raises(TypeError, match="hist_gen must be a pandas.DataFrame"):
+        plot_generation_sim_vs_hist(scenario, 3, "Texas")
+    with pytest.raises(TypeError, match="state must be a str"):
+        plot_generation_sim_vs_hist(scenario, pd.DataFrame(), ["Texas"])
+
+
+def test_plot_generation_sim_vs_hist_argument_value():
+    with pytest.raises(ValueError, match="Invalid state"):
+        plot_generation_sim_vs_hist(scenario, hist_gen, "Washington")
+
+
+def test_plot_generation_sim_vs_hist():
+    plot_generation_sim_vs_hist(
+        scenario, hist_gen, "Texas", show_max=False, plot_show=False
+    )
+    plot_generation_sim_vs_hist(scenario, hist_gen, "Texas", plot_show=False)