fix^N

test/traversals/eulerian.jl

@@ -7,7 +7,7 @@
     # a tour (different start/end)
     g1 = SimpleGraph([Edge(1,2), Edge(2,3), Edge(3,4)])
     @test eulerian(g1, 1) == [1,2,3,4]
-    @test_throws ErrorException("starting vertex has even degree but there are other vertices with odd degree") eulerian(g1, 2)
+    @test_throws ErrorException("starting vertex has even degree but there are other vertices with odd degree: a eulerian cycle does not exist") eulerian(g1, 2)
 
     # a cycle with a node (vertex 2) with multiple neighbors
     g2 = SimpleGraph([Edge(1,2), Edge(2,3), Edge(3,4), Edge(4,1), Edge(2,5), Edge(5,6), 
@@ -16,20 +16,20 @@
 
     # graph with odd-degree vertices
     g3 = SimpleGraph([Edge(1,2), Edge(2,3), Edge(3,4), Edge(2,4), Edge(4,1), Edge(4,2)])
-    @test_throws ErrorException("starting vertex has even degree but there are other vertices with odd degree") eulerian(g3, 1)
+    @test_throws ErrorException("starting vertex has even degree but there are other vertices with odd degree: a eulerian cycle does not exist") eulerian(g3, 1)
 
     # start/end point not in graph
     @test_throws ErrorException("starting vertex is not in the graph") eulerian(g3, 5)
 
     # disconnected components
     g4 = SimpleGraph([Edge(1,2), Edge(2,3), Edge(3,1),  # component 1
                       Edge(4,5), Edge(5,6), Edge(6,4)]) # component 2
-    @test_throws ErrorException("graph is not connected") eulerian(g4)
+    @test_throws ErrorException("graph is not connected: a eulerian cycle/trail does not exist") eulerian(g4)
 
     # zero-degree nodes
     g5 = SimpleGraph(4)
     add_edge!(g5, Edge(1,2)); add_edge!(g5, Edge(2,3)); add_edge!(g5, Edge(3,1))
-    @test_throws ErrorException("some vertices have degree zero") eulerian(g5)
+    @test_throws ErrorException("some vertices have degree zero (are isolated) and cannot be reached") eulerian(g5)
 
     # not yet implemented for directed graphs
     @test_broken eulerian(SimpleDiGraph([Edge(1,2), Edge(2,3), Edge(3,1)]))