fix the omnivory test

test/community/foodwebs.jl

@@ -1,19 +1,26 @@
 module TestFoodWebs
-  using Test
-  using EcologicalNetworks
+using Test
+using EcologicalNetworks
 
-  # test trophic levels on motifs
-  s1 = unipartitemotifs()[:S1]
-  s1_ftl = trophic_level(s1)
-  s1_tl = distance_to_producer(s1)
-  @test maximum(values(s1_ftl)) ≈ 3
-  @test maximum(values(s1_tl)) ≈ 3.0
-  @test s1_ftl[:a] ≈ 3
-  @test s1_ftl[:b] ≈ 2
-  @test s1_ftl[:c] ≈ 1
+# test trophic levels on motifs
+s1 = unipartitemotifs()[:S1]
+s1_ftl = trophic_level(s1)
+s1_tl = distance_to_producer(s1)
+@test maximum(values(s1_ftl)) ≈ 3
+@test maximum(values(s1_tl)) ≈ 3.0
+@test s1_ftl[:a] ≈ 3
+@test s1_ftl[:b] ≈ 2
+@test s1_ftl[:c] ≈ 1
 
-  s2 = unipartitemotifs()[:S2]
-  @test minimum(values(trophic_level(s1))) ≈ 1.0
-  @test minimum(values(distance_to_producer(s1))) == 1.0
+s2 = unipartitemotifs()[:S2]
+@test minimum(values(trophic_level(s1))) ≈ 1.0
+@test minimum(values(distance_to_producer(s1))) == 1.0
+
+# Test for omnivory
+for s in species(s1)
+    if iszero(EcologicalNetworks.degree_out(s1)[s])
+        @test iszero(omnivory(s1)[s])
+    end
+end
 
 end