add unit tests for store previous Jacobian option

Author: MaxenceGollier

test/runtests.jl

@@ -48,7 +48,8 @@ for (op, composite_op, shifted_op) ∈
     y = similar(x)
     ν = 0.1056
     prox!(y, ϕ, x, ν)
-
+    @test ϕ.full_row_rank == true
+    
     if "$op" == "NormL2"
       y_true = [0.24545429, 0.75250248, -0.66619752, 1.19372286]
       norm = Op(1.0)
@@ -63,6 +64,31 @@ for (op, composite_op, shifted_op) ∈
     @test ϕ.A == SparseMatrixCOO(Float64[2 0 0 -1; 0 1 1 0])
     @test ϕ(ones(Float64, 4)) ==
           h([1.0, 2.0] + SparseMatrixCOO(Float64[2 0 0 -1; 0 1 1 0])*ones(Float64, 4))
+    
+    # test store previous Jacobian option
+
+    function c_store_prev!(z, x)
+      z[1] = 2*x[1]^2 - x[4]
+      z[2] = x[2] + x[3]
+    end
+    function J_store_prev!(z, x)
+      z.vals .= Float64[4.0*x[1], 1.0, 1.0, -1.0]
+    end
+    ψ_store_prev = CompositeOp(λ, c_store_prev!, J_store_prev!, A, b, store_previous_jacobian = true)
+    @test ψ_store_prev.store_previous_jacobian == true
+
+    xk = [1.0, 0.0, 0.0, 0.0]
+    ϕ_store_prev = shifted(ψ_store_prev, xk)
+    @test !isnothing(ϕ_store_prev.A_prev)
+
+    @test all(ϕ_store_prev.A_prev .== ϕ_store_prev.A)  # A_prev should be a copied version of A at this point
+    @test all(ϕ_store_prev.A .== SparseMatrixCOO([4.0 0.0 0.0 -1.0; 0.0 1.0 1.0 0.0]))
+
+    xk = [2.0, 0.0, 0.0, 0.0]
+    shift!(ϕ_store_prev, xk)
+    @test all(ϕ_store_prev.A_prev .== SparseMatrixCOO([4.0 0.0 0.0 -1.0; 0.0 1.0 1.0 0.0]))
+    @test all(ϕ_store_prev.A .== SparseMatrixCOO([8.0 0.0 0.0 -1.0; 0.0 1.0 1.0 0.0]))
+
 
     # test different types
     h = Op(Float32(λ))
@@ -101,6 +127,7 @@ for (op, composite_op, shifted_op) ∈
     y = similar(x)
     ν = 0.1056
     prox!(y, ϕ, x, ν)
+    @test ϕ.full_row_rank == false
     if "$op" == "NormL2"
       y_true = [0.33642, 1.1287, -0.29, 1.14824]
       norm = Op(1.0)