TST: fix test_dirint_array_inputs to use 2 time points

Author: Omesh37

tests/test_irradiance.py

@@ -1141,20 +1141,21 @@ def test_dirindex_min_cos_zenith_max_zenith():
 
 
 def test_dirint_array_inputs():
-    """np.array inputs work correctly. GH #2751"""
-    times = pd.DatetimeIndex(['2023-06-21 12:00'], tz='UTC')
+    """np.array and pd.Series inputs work correctly. GH #2751"""
+    # dirint requires >= 2 time points
+    times = pd.date_range('2023-06-21 10:00', periods=2, freq='h', tz='UTC')
 
-    # np.array input (1-element) -- return pd.Series
+    # np.array input → should return pd.Series
     result = irradiance.dirint(
-        ghi=np.array([500.0]),
-        solar_zenith=np.array([45.0]),
+        ghi=np.array([500.0, 400.0]),
+        solar_zenith=np.array([45.0, 50.0]),
         times=times,
         use_delta_kt_prime=False
     )
     assert isinstance(result, pd.Series)
     assert result.iloc[0] > 0
 
-    # pd.Series input -- return pd.Series
+    # pd.Series input → should return pd.Series
     times2 = pd.date_range('2023-06-21 10:00', periods=3, freq='h', tz='UTC')
     result2 = irradiance.dirint(
         ghi=pd.Series([400, 500, 300], index=times2),
@@ -1164,6 +1165,15 @@ def test_dirint_array_inputs():
     assert isinstance(result2, pd.Series)
     assert (result2 >= 0).all()
 
+    # single time point → ValueError regardless of use_delta_kt_prime
+    times_single = pd.DatetimeIndex(['2023-06-21 12:00'], tz='UTC')
+    with pytest.raises(ValueError, match="requires at least two times"):
+        irradiance.dirint(
+            ghi=np.array([500.0]),
+            solar_zenith=np.array([45.0]),
+            times=times_single
+        )
+
 
 def test_dni():
     ghi = pd.Series([90, 100, 100, 100, 100])