Test in-place action of plans

Author: gaurav-arya

src/TestUtils.jl

@@ -42,18 +42,22 @@ function test_fft_backend(array_constructor)
               18.0+0.0im  -4.5+2.598076211353316im  -4.5-2.598076211353316im]),
         )
             x = array_constructor(_x)
+            xcopy_float = array_constructor(copy(float.(x)))
+            xcopy_complex = array_constructor(copy(complex.(xcopy_float)))
             fftw_fft = array_constructor(_fftw_fft)
 
             # FFT
             dims = ndims(x)
             y = AbstractFFTs.fft(x, dims)
+            ycopy = array_constructor(copy(y))
             @test y ≈ fftw_fft
             # test plan_fft and also inv and plan_inv of plan_ifft, which should all give 
             # functionally identical plans
             for P in [plan_fft(x, dims), inv(plan_ifft(x, dims)), 
                       AbstractFFTs.plan_inv(plan_ifft(x, dims))]
                 @test eltype(P) <: Complex
                 @test P * x ≈ fftw_fft
+                @test mul!(ycopy, P, x) ≈ fftw_fft
                 @test P \ (P * x) ≈ x
                 @test fftdims(P) == dims
             end
@@ -64,6 +68,7 @@ function test_fft_backend(array_constructor)
             P = plan_bfft(x, dims)
             @test P * y ≈ fftw_bfft
             @test P \ (P * y) ≈ y
+            @test mul!(xcopy_complex, P, y) ≈ fftw_bfft
             @test fftdims(P) == dims
 
             # IFFT
@@ -72,6 +77,7 @@ function test_fft_backend(array_constructor)
             for P in [plan_ifft(x, dims), inv(plan_fft(x, dims)), 
                       AbstractFFTs.plan_inv(plan_fft(x, dims))]
                 @test P * y ≈ fftw_ifft
+                @test mul!(xcopy_complex, P, y) ≈ fftw_ifft
                 @test P \ (P * y) ≈ y
                 @test fftdims(P) == dims
             end
@@ -82,11 +88,13 @@ function test_fft_backend(array_constructor)
                 1:(size(fftw_fft, ndims(fftw_fft)) ÷ 2 + 1)
             ]
             ry = AbstractFFTs.rfft(x, dims)
+            rycopy = array_constructor(copy(ry))
             @test ry ≈ fftw_rfft
             for P in [plan_rfft(x, dims), inv(plan_irfft(ry, size(x, dims), dims)), 
                       AbstractFFTs.plan_inv(plan_irfft(ry, size(x, dims), dims))]
                 @test eltype(P) <: Real
                 @test P * x ≈ fftw_rfft
+                @test mul!(rycopy, P, x) ≈ fftw_rfft
                 @test P \ (P * x) ≈ x
                 @test fftdims(P) == dims
             end
@@ -96,6 +104,7 @@ function test_fft_backend(array_constructor)
             @test AbstractFFTs.brfft(ry, size(x, dims), dims) ≈ fftw_brfft
             P = plan_brfft(ry, size(x, dims), dims)
             @test P * ry ≈ fftw_brfft
+            @test mul!(xcopy_float, P, ry) ≈ fftw_brfft
             @test P \ (P * ry) ≈ ry
             @test fftdims(P) == dims
 
@@ -105,6 +114,7 @@ function test_fft_backend(array_constructor)
             for P in [plan_irfft(ry, size(x, dims), dims), inv(plan_rfft(x, dims)), 
                       AbstractFFTs.plan_inv(plan_rfft(x, dims))]
                 @test P * ry ≈ fftw_irfft
+                @test mul!(xcopy_float, P, ry) ≈ fftw_irfft
                 @test P \ (P * ry) ≈ ry
                 @test fftdims(P) == dims
             end