Test reshaping check

src/Reshaping.jl

@@ -18,8 +18,8 @@ function reshape_supercell(sys::System, shape)
 
     orig = orig_crystal(sys)
     check_shape_commensurate(orig, shape)
-
-    shape_in_prim = primitive_cell(orig) \ shape
+    prim_cell = @something primitive_cell(orig) Mat3(I)
+    shape_in_prim = prim_cell \ shape
     @assert all_integer(shape_in_prim; orig.symprec)
     shape_in_prim = round.(Int, shape_in_prim)
 

src/Symmetry/Crystal.jl

@@ -499,17 +499,13 @@ end
 
 
 function check_shape_commensurate(cryst, shape)
-    # Primitive lattice vectors in global Cartesian coordinates
-    prim_cell = primitive_cell(cryst)
-
-    if isnothing(prim_cell)
-        if !all_integer(shape; cryst.symprec)
-            error("Cell shape must be a 3×3 matrix of integers. Received $shape.")
-        end
-    else
-        shape_in_prim = prim_cell \ shape
-        if !all_integer(shape_in_prim; cryst.symprec)
-            error("Cell shape must be integer multiples of primitive lattice vectors. Calculated $shape_in_prim.")
+    prim_cell = @something primitive_cell(cryst) Mat3(I)
+    shape_in_prim = prim_cell \ shape
+    if !all_integer(shape_in_prim; cryst.symprec)
+        if prim_cell ≈ I
+            error("Elements of `shape` must be integer. Received $shape.")
+        else
+            error("Elements of `primitive_cell(cryst) \\ shape` must be integer. Calculated $shape_in_prim.")
         end
     end
 end

src/deprecated.jl

@@ -120,4 +120,4 @@ end
 # * Missing μ0_μB² in enable_dipole_dipole! and
 #   modify_exchange_with_truncated_dipole_dipole!
 # * energy_ϵ argument in SpinWaveTheory
-# * setting argument in Crystal
+# * setting argument in Crystal

test/test_resize.jl

@@ -52,6 +52,31 @@
     @test energy_per_site(newsys) ≈ 2.55
 end
 
+
+@testitem "Validate reshaping" begin
+    using LinearAlgebra
+
+    latvecs = lattice_vectors(1, 1, 1, 90, 90, 90)
+    positions = [[0, 0, 0]/2, [1, 1, 1]/2]
+    cryst = Crystal(latvecs, positions)
+    sys = System(cryst, [1 => Moment(s=1, g=2)], :dipole)
+
+    primcell = primitive_cell(cryst)
+    reshape_supercell(sys, Diagonal([2, 3, 4])) # Fine
+    reshape_supercell(sys, primcell) # Fine
+    reshape_supercell(sys, primcell * Diagonal([2, 3, 4])) # Fine
+    msg = "Elements of `primitive_cell(cryst) \\ shape` must be integer. Calculated [3.5 0.5 -0.5; 1.0 3.0 -1.0; 0.5 -0.5 2.5]."
+    @test_throws msg reshape_supercell(sys, Diagonal([2, 3, 4]) * primcell)
+
+    positions = [[0, 0, 0]]
+    cryst = Crystal(latvecs, positions)
+    sys = System(cryst, [1 => Moment(s=1, g=2)], :dipole)
+    reshape_supercell(sys, Diagonal([2.0, 3, 4]))
+    msg = "Elements of `shape` must be integer. Received [2.5 0.0 0.0; 0.0 3.0 0.0; 0.0 0.0 4.0]."
+    @test_throws msg reshape_supercell(sys, Diagonal([2.5, 3, 4]))
+end
+
+
 @testitem "Equivalent reshaping" begin
     using LinearAlgebra