Fix 113 and add regression (#114)

Signed-off-by: Don MacMillen <don@macmillen.net>

Author: macd

src/operations/extract.jl

@@ -134,7 +134,7 @@ function extract!(
     w::AbstractGBVector, u::AbstractGBVector, I;
     mask = nothing, accum = nothing, desc = nothing
 )
-    _canbeoutput(C) || throw(ShallowException())
+    _canbeoutput(w) || throw(ShallowException())
     I, ni = idx(I)
     I = decrement!(I)
     desc = _handledescriptor(desc; out=w)
@@ -151,4 +151,4 @@ function extract(
     wlen = _outlength(u, I)
     w = similar(u, wlen)
     return extract!(w, u, I; mask, accum, desc)
-end
+end

test/operations/extract.jl

@@ -0,0 +1,5 @@
+@testset "extract" begin
+    m = GBVector([1,2,3,4,5,6])
+    #extract correctness
+    @test all(m[1:3] .== [1,2,3])
+end

test/runtests.jl

@@ -78,6 +78,7 @@ println("$(SuiteSparseGraphBLAS.get_lib())")
     include_test("types.jl")
     include_test("issues.jl")
     include_test("operations/ewise.jl")
+    include_test("operations/extract.jl")
     include_test("operations/kron.jl")
     include_test("operations/map.jl")
     include_test("operations/mul.jl")