Add Random Walk test

test/known_graphs.jl

@@ -1,6 +1,9 @@
 using MetagraphOptimization
+using Random
 using Test
 
+Random.seed!(0)
+
 function test_known_graphs()
     g_ABAB = import_txt(joinpath(@__DIR__, "..", "examples", "AB->AB.txt"))
     props = graph_properties(g_ABAB)
@@ -12,6 +15,7 @@ function test_known_graphs()
     @test length(generate_options(g_ABAB).nodeFusions) == 10
 
     test_node_fusion(g_ABAB)
+    test_random_walk(g_ABAB, 100)
 
 
     g_ABAB3 = import_txt(joinpath(@__DIR__, "..", "examples", "AB->ABBB.txt"))
@@ -22,9 +26,10 @@ function test_known_graphs()
     @test props.data == 828
 
     test_node_fusion(g_ABAB3)
+    test_random_walk(g_ABAB3, 1000)
 end
 
-function test_node_fusion(g)
+function test_node_fusion(g::DAG)
     props = graph_properties(g)
 
     options = generate_options(g)
@@ -50,6 +55,47 @@ function test_node_fusion(g)
 
         options = generate_options(g)
     end
-
-    print(g)
+end
+
+function test_random_walk(g::DAG, n::Int64)
+    # the purpose here is to do "random" operations and reverse them again and validate that the graph stays the same and doesn't diverge
+    reset_graph!(g)
+
+    properties = graph_properties(g)
+
+    println("Random Walking... ")
+
+    for i = 1:n
+        print("\r", i)
+        # choose push or pop
+        if rand(Bool)
+            # push
+            opt = generate_options(g)
+
+            # choose one of fuse/split/reduce
+            option = rand(1:3)
+            if option == 1 && !isempty(opt.nodeFusions)
+                push_operation!(g, opt.nodeFusions[rand(1 : length(opt.nodeFusions))])
+            elseif option == 2 && !isempty(opt.nodeReductions)
+                push_operation!(g, opt.nodeReductions[rand(1 : length(opt.nodeReductions))])
+            elseif option == 3 && !isempty(opt.nodeSplits)
+                push_operation!(g, opt.nodeSplits[rand(1 : length(opt.nodeSplits))])
+            else
+                i = i-1
+            end
+        else
+            # pop
+            if (can_pop(g))
+                pop_operation!(g)
+            else
+                i = i-1
+            end
+        end
+    end
+
+    println("\rDone.")
+
+    reset_graph!(g)
+
+    @test properties == graph_properties(g)
 end