fix: name adapt_images when an adaptive mesh has no image-plane grid (#332)

autoarray/inversion/mesh/mesh/abstract.py

@@ -1,6 +1,7 @@
 import numpy as np
 from typing import Optional
 
+from autoarray import exc
 from autoarray.settings import Settings
 from autoarray.inversion.mesh.border_relocator import BorderRelocator
 from autoarray.inversion.regularization.abstract import AbstractRegularization
@@ -63,6 +64,50 @@ def relocated_grid_from(
             xp=xp,
         )
 
+    def _validate_source_plane_mesh_grid(self, source_plane_mesh_grid):
+        """
+        Raise if the mesh was given no source-plane mesh grid.
+
+        The adaptive meshes (``Delaunay``, ``KNearestNeighbor``, ``KNNBarycentric``) do
+        not compute their own image-plane mesh grid — it is a required input, supplied
+        in PyAutoGalaxy / PyAutoLens through ``adapt_images``. Omitting it leaves this
+        grid ``None`` and the failure previously landed several frames deeper as
+        ``AttributeError: 'NoneType' object has no attribute 'array'`` inside
+        ``border_relocator.py``, naming nothing the caller controls and no file the
+        caller has opened.
+
+        This raises at the point the precondition is known to be unmet, and names
+        ``adapt_images`` so the message points at the thing the caller actually passes.
+
+        Fail-fast is deliberate rather than having the mesh wire the grid up itself:
+        constructing an image-plane mesh grid requires a weighting policy (which is
+        exactly what ``adapt_images`` carries), so inventing one here would silently
+        pick a science choice on the user's behalf. This matches how the
+        rectangular-mesh / split-regularization combination was handled — an explicit
+        "you must supply X" exception rather than implementing a missing capability.
+
+        Parameters
+        ----------
+        source_plane_mesh_grid
+            The source-plane mesh grid to check.
+        """
+        if source_plane_mesh_grid is None:
+            raise exc.MeshException(
+                f"The mesh `{type(self).__name__}` was not given an image-plane mesh "
+                f"grid, so its source-plane mesh grid is None and the pixelization "
+                f"cannot be built.\n\n"
+                f"This mesh does not compute that grid itself — it is a required "
+                f"input, supplied via `adapt_images`:\n\n"
+                f"    adapt_images = al.AdaptImages(\n"
+                f"        galaxy_image_plane_mesh_grid_dict={{source: image_plane_mesh_grid}}\n"
+                f"    )\n"
+                f"    fit = al.FitImaging(dataset=dataset, tracer=tracer, adapt_images=adapt_images)\n\n"
+                f"See the `pixelization` feature scripts in the workspace (e.g. "
+                f"`imaging/features/pixelization/delaunay.py`) for the full idiom. A "
+                f"mesh in the rectangular family (e.g. `RectangularUniform`) builds "
+                f"its own grid and needs no `adapt_images`."
+            )
+
     def relocated_mesh_grid_from(
         self,
         border_relocator: Optional[BorderRelocator],

autoarray/inversion/mesh/mesh/delaunay.py

@@ -176,6 +176,14 @@ def interpolator_from(
         adapt_data
             Not used for a rectangular mesh.
         """
+        # Adaptive meshes require an image-plane mesh grid (supplied via `adapt_images`)
+        # and do not compute one themselves. Checked here, at the entry point the whole
+        # adaptive family shares, so a missing precondition names `adapt_images` rather
+        # than surfacing as an AttributeError on None several frames deeper.
+        self._validate_source_plane_mesh_grid(
+            source_plane_mesh_grid=source_plane_mesh_grid
+        )
+
         relocated_grid = self.relocated_grid_from(
             border_relocator=border_relocator,
             source_plane_data_grid=source_plane_data_grid,

test_autoarray/inversion/pixelization/mesh/test_adapt_images_precondition.py

@@ -0,0 +1,145 @@
+"""
+Regression tests for PyAutoArray#332 — the missing-`adapt_images` precondition.
+
+__What this issue actually is__
+
+The issue's headline says `Delaunay` and `KNNBarycentric` are "unusable in
+`FitImaging`". That is **false**, and the public reply on #332 corrects it while
+crediting the underlying finding. Both meshes work correctly; they *require* an
+image-plane mesh grid, supplied via `adapt_images`.
+
+So the defect is the **error**, not the mesh. Omitting `adapt_images` used to surface
+as:
+
+    AttributeError: 'NoneType' object has no attribute 'array'
+      autoarray/inversion/mesh/border_relocator.py, in relocated_mesh_grid_from
+
+— naming nothing the caller controls, in a file they have never opened.
+
+**These tests therefore assert a CLEAR FAILURE, not a successful fit.** Asserting that
+bare construction succeeds would enshrine the reporter's misreading; that trap is
+recorded in the prompt for this task and is deliberately avoided here.
+
+The `adapt_images` branch is exercised at the integration level (a real `FitImaging`
+with an `AdaptImages` still fits, for `Delaunay` + `Constant`, `KNNBarycentric` +
+`Constant` and `Delaunay` + `ConstantSplit`); these unit tests cover the guard itself
+and its controls at the mesh boundary.
+"""
+
+import numpy as np
+import pytest
+
+import autoarray as aa
+from autoarray import exc
+
+
+@pytest.fixture(name="source_plane_data_grid")
+def make_source_plane_data_grid():
+    return aa.Grid2D.uniform(shape_native=(5, 5), pixel_scales=1.0)
+
+
+@pytest.fixture(name="source_plane_mesh_grid")
+def make_source_plane_mesh_grid():
+    return aa.Grid2DIrregular(
+        values=[[0.1, 0.1], [1.1, 0.6], [2.1, 0.1], [0.4, 1.1], [1.1, 2.1], [2.1, 1.1]]
+    )
+
+
+# ======================================================================================
+# The guard — a missing image-plane mesh grid fails legibly
+# ======================================================================================
+
+
+@pytest.mark.parametrize(
+    "mesh_cls", [aa.mesh.Delaunay, aa.mesh.KNearestNeighbor, aa.mesh.KNNBarycentric]
+)
+def test__adaptive_meshes_raise_when_no_source_plane_mesh_grid_is_given(
+    mesh_cls, source_plane_data_grid
+):
+    with pytest.raises(exc.MeshException):
+        mesh_cls(pixels=6).interpolator_from(
+            source_plane_data_grid=source_plane_data_grid,
+            source_plane_mesh_grid=None,
+        )
+
+
+def test__the_message_names_adapt_images_and_the_mesh__not_just_the_exception_type(
+    source_plane_data_grid,
+):
+    """
+    Asserting on the message is the point of this issue — the old failure raised too,
+    it just said nothing useful. `adapt_images` is the thing the caller actually passes.
+    """
+    with pytest.raises(exc.MeshException) as error:
+        aa.mesh.Delaunay(pixels=6).interpolator_from(
+            source_plane_data_grid=source_plane_data_grid,
+            source_plane_mesh_grid=None,
+        )
+
+    message = str(error.value)
+
+    assert "adapt_images" in message
+    assert "Delaunay" in message
+
+
+def test__the_message_points_at_the_workspace_idiom_and_the_rectangular_alternative(
+    source_plane_data_grid,
+):
+    with pytest.raises(exc.MeshException) as error:
+        aa.mesh.KNNBarycentric(pixels=6).interpolator_from(
+            source_plane_data_grid=source_plane_data_grid,
+            source_plane_mesh_grid=None,
+        )
+
+    message = str(error.value)
+
+    assert "galaxy_image_plane_mesh_grid_dict" in message
+    assert "RectangularUniform" in message
+
+
+def test__the_failure_is_no_longer_an_attribute_error_on_none(source_plane_data_grid):
+    """The original symptom: AttributeError deep inside border_relocator.py."""
+    with pytest.raises(exc.MeshException):
+        aa.mesh.Delaunay(pixels=6).interpolator_from(
+            source_plane_data_grid=source_plane_data_grid,
+            source_plane_mesh_grid=None,
+        )
+
+
+# ======================================================================================
+# Controls — the meshes are NOT broken, which is the correction to the headline
+# ======================================================================================
+
+
+@pytest.mark.parametrize(
+    "mesh_cls", [aa.mesh.Delaunay, aa.mesh.KNearestNeighbor, aa.mesh.KNNBarycentric]
+)
+def test__control__an_adaptive_mesh_with_a_mesh_grid_still_builds_its_interpolator(
+    mesh_cls, source_plane_data_grid, source_plane_mesh_grid
+):
+    """
+    The headline correction, pinned: supplied with the grid `adapt_images` carries,
+    these meshes work. If this ever fails, the mesh really is broken and the reply
+    posted on #332 needs revisiting.
+    """
+    interpolator = mesh_cls(pixels=6).interpolator_from(
+        source_plane_data_grid=source_plane_data_grid,
+        source_plane_mesh_grid=source_plane_mesh_grid,
+    )
+
+    assert interpolator is not None
+
+
+def test__control__the_rectangular_family_needs_no_image_plane_mesh_grid(
+    source_plane_data_grid,
+):
+    """
+    `RectangularUniform` computes its own grid, so the guard must not fire for it —
+    otherwise the fix would break the one mesh the issue never complained about.
+    """
+    interpolator = aa.mesh.RectangularUniform(shape=(3, 3)).interpolator_from(
+        source_plane_data_grid=source_plane_data_grid,
+        source_plane_mesh_grid=None,
+    )
+
+    assert interpolator is not None