Add unit test demonstrating the bug

Author: WilliamJamieson

gwcs/tests/test_wcs.py

@@ -1813,3 +1813,25 @@ def test_direct_numerical_inverse(gwcs_romanisim):
     out = gwcs_romanisim.numerical_inverse(*ra_dec)
 
     assert_allclose(xy, out)
+
+
+def test_array_high_level_output():
+    """
+    Test that we don't loose array values when requesting a high-level output
+    from a WCS object.
+    """
+    input_frame = cf.CoordinateFrame(
+        naxes=1,
+        axes_type=("SPATIAL",),
+        axes_order=(0,),
+        name="pixels",
+        unit=(u.pix,),
+        axes_names=("x",),
+    )
+    output_frame = cf.SpectralFrame(unit=(u.nm,), axes_names=("lambda",))
+    wave_model = models.Scale(0.1) | models.Shift(500)
+    gwcs = wcs.WCS([(input_frame, wave_model), (output_frame, None)])
+    assert (
+        gwcs(np.array([0, 1, 2]), with_units=True)
+        == coord.SpectralCoord([500, 500.1, 500.2] * u.nm)
+    ).all()