make test matrix not just diagonal

Author: ElOceanografo

test/rulesets/SparseArrays/sparsematrix.jl

@@ -35,9 +35,9 @@ end
 end
 
 @testset "[log[abs[det]]] SparseMatrixCSC" begin
-    ii = 1:5
-    jj = 1:5
-    x = ones(5)
+    ii = [1:5; 2; 4]
+    jj = [1:5; 4; 2]
+    x = [ones(5); 0.1; 0.1]
     A = sparse(ii, jj, x)
     test_rrule(logabsdet, A)
     test_rrule(logdet, A)