optimize test for heterograph (#370)

Author: askorupka

test/layers/heteroconv.jl

@@ -1,6 +1,7 @@
 @testset "HeteroGraphConv" begin
     d, n = 3, 5
     g = rand_bipartite_heterograph(n, 2*n, 15)
+    hg = rand_bipartite_heterograph((2,3), 6)
 
     model = HeteroGraphConv([(:A,:to,:B) => GraphConv(d => d), 
                             (:B,:to,:A) => GraphConv(d => d)])
@@ -93,20 +94,18 @@
     end
 
     @testset "CGConv" begin
-        g = rand_bipartite_heterograph((2,3), 6)
         x = (A = rand(Float32, 4,2), B = rand(Float32, 4, 3))
         layers = HeteroGraphConv( (:A, :to, :B) => CGConv(4 => 2, relu),
                                     (:B, :to, :A) => CGConv(4 => 2, relu));
-        y = layers(g, x); 
+        y = layers(hg, x); 
         @test size(y.A) == (2,2) && size(y.B) == (2,3)
     end
 
     @testset "EdgeConv" begin
-        g = rand_bipartite_heterograph((2,3), 6)
         x = (A = rand(Float32, 4,2), B = rand(Float32, 4, 3))
         layers = HeteroGraphConv( (:A, :to, :B) => EdgeConv(Dense(2 * 4, 2), aggr = +),
                                     (:B, :to, :A) => EdgeConv(Dense(2 * 4, 2), aggr = +));
-        y = layers(g, x); 
+        y = layers(hg, x); 
         @test size(y.A) == (2,2) && size(y.B) == (2,3)
     end