Improve the code coverage for the postprocessing

Author: amontoison

test/small.jl

@@ -97,6 +97,14 @@ end;
                        "Arrowhead"     => Dict(:direct       => Dict(:all_colors => (0,0), :row_colors => (0,0), :column_colors => (0,0)),
                                                :substitution => Dict(:all_colors => (0,0), :row_colors => (0,0), :column_colors => (0,0))))
 
+    @testset "coverage postprocessing for acyclic bicoloring" begin
+        problem = ColoringProblem(; structure=:nonsymmetric, partition=:bidirectional)
+        order = RandomOrder(StableRNG(4), 4)
+        algo = GreedyColoringAlgorithm(order; decompression=:substitution, postprocessing=true)
+        A = sparse([1 1 0; 0 0 1; 0 1 0])
+        result = coloring(A, problem, algo)
+    end
+
     @testset "postprocessing_minimizes = :sym_colors" begin
         problem = ColoringProblem(; structure=:nonsymmetric, partition=:bidirectional)
         order = NaturalOrder()