Test that diff(T[:,1:5]) * randn(5) returns an Expansion instead of a lazy multiplication

Author: dlfivefifty

Project.toml

@@ -39,7 +39,7 @@ HypergeometricFunctions = "0.3.4"
 InfiniteArrays = " 0.14"
 InfiniteLinearAlgebra = "0.8"
 IntervalSets = "0.7"
-LazyArrays = "2.0.3"
+LazyArrays = "2.1.10"
 LazyBandedMatrices = "0.10"
 QuasiArrays = "0.11"
 SpecialFunctions = "1.0, 2"

test/test_chebyshev.jl

@@ -578,6 +578,10 @@ import BandedMatrices: isbanded
         @test T \ exp.(im*x) ≈ transform(T, x -> exp(im*x))
         @test expand(T, x -> exp(im*x))[0.1] ≈ exp(im*0.1)
     end
+
+    @testset "diff of truncation" begin
+        MemoryLayout(diff(ChebyshevT()[:,1:5]) * randn(5)) isa ExpansionLayout
+    end
 end
 
 struct QuadraticMap{T} <: Map{T} end