Add node fusion test

test/known_graphs.jl

@@ -2,7 +2,6 @@ using MetagraphOptimization
 using Test
 
 function test_known_graphs()
-
     g_ABAB = import_txt(joinpath(@__DIR__, "..", "examples", "AB->AB.txt"))
     props = graph_properties(g_ABAB)
 
@@ -10,4 +9,46 @@ function test_known_graphs()
     @test props.compute_effort == 185
     @test props.data == 102
 
+    @test length(generate_options(g_ABAB).fusions) == 10
+
+    test_node_fusion(g_ABAB)
+
+
+    g_ABAB3 = import_txt(joinpath(@__DIR__, "..", "examples", "AB->ABBB.txt"))
+    props = graph_properties(g_ABAB3)
+
+    @test length(g_ABAB3.nodes) == 280
+    @test props.compute_effort == 2007
+    @test props.data == 828
+
+    test_node_fusion(g_ABAB3)
+end
+
+function test_node_fusion(g)
+    props = graph_properties(g)
+
+    options = generate_options(g)
+
+    nodes_number = length(g.nodes)
+    data = props.data
+    compute_effort = props.compute_effort
+
+    while length(options.fusions) != 0
+        fusion = options.fusions[1]
+        n = node_fusion(g, fusion[1], fusion[2], fusion[3])
+        @test typeof(n.task) <: FusedComputeTask
+        @test length(g.nodes) == nodes_number - 2
+
+        props = graph_properties(g)
+        @test props.data < data
+        @test props.compute_effort == compute_effort
+
+        nodes_number = length(g.nodes)
+        data = props.data
+        compute_effort = props.compute_effort
+
+        options = generate_options(g)
+    end
+
+    print(g)
 end