added unit tests for directed line graph

Author: lampretl

Project.toml

@@ -7,7 +7,6 @@ ArnoldiMethod = "ec485272-7323-5ecc-a04f-4719b315124d"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 Inflate = "d25df0c9-e2be-5dd7-82c8-3ad0b3e990b9"
-JuliaFormatter = "98e50ef6-434e-11e9-1051-2b60c6c9e899"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 SharedArrays = "1a1011a3-84de-559e-8e89-a11a2f7dc383"

test/operators.jl

@@ -352,6 +352,48 @@
     @testset "Length: $(typeof(g))" for g in test_generic_graphs(SimpleGraph(100))
         @test length(g) == 10000
     end
+
+    @testset "Undirected Line Graph" begin
+        @testset "Undirected Cycle Graphs" begin
+            for n in 3:9
+                g = cycle_graph(n)
+                lg = line_graph(g)  # checking if lg is an n-cycle
+                @test nv(lg) == n
+                @test ne(lg) == n
+                @test is_connected(lg)
+                @test all(degree(lg, v) == 2 for v in vertices(lg))
+            end
+        end
+
+        @testset "Undirected Path Graphs" begin
+            for n in 2:9
+                g = path_graph(n)
+                lg = line_graph(g)  # checking if lg is an n-1-path
+                @test nv(lg) == n - 1
+                @test ne(lg) == n - 2
+                @test is_connected(lg)
+                @test all(degree(lg, v) <= 2 for v in vertices(lg))
+                @test any(degree(lg, v) == 1 for v in vertices(lg)) || n == 2 && ne(lg) == 0
+            end
+        end
+
+        @testset "Undirected Star Graphs" begin
+            for n in 3:9
+                g = star_graph(n)
+                lg = line_graph(g)  # checking if lg is a complete graph on n-1 vertices
+                @test nv(lg) == n - 1
+                @test ne(lg) == binomial(n - 1, 2)  # lg must be a complete graph
+            end
+        end
+
+        @testset "Undirected Self-loops" begin
+            g = SimpleGraph(2, [[2], [1, 2], Int[]])
+            lg = line_graph(g)
+            @test nv(lg) == 2  # only 2 edges (self-loop counts once)                                                                                                                                                                           
+            @test ne(lg) == 1  # only connection between edge 1-2 and self-loop 2-2                                                                                                                                                               
+        end
+    end
+
     @testset "Directed Line Graph" begin
         @testset "Directed Cycle Graphs" begin
             for n in 3:9
@@ -360,6 +402,7 @@
                 @test nv(lg) == n
                 @test ne(lg) == n
                 @test is_directed(lg)
+                @test is_connected(lg)
                 @test all(outdegree(lg, v) == 1 for v in vertices(lg))
                 @test all(indegree(lg, v) == 1 for v in vertices(lg))
             end
@@ -373,91 +416,32 @@
                 @test ne(lg) == n - 2
                 @test is_directed(lg)
                 @test is_connected(lg)
-                @test all(outdegree(lg, v) <= 1 for v in vertices(lg))
-                @test all(indegree(lg, v) <= 1 for v in vertices(lg))
-                if n > 2
-                    @test indegree(lg, 1) == 0
-                    @test outdegree(lg, 1) == 1
-                    @test indegree(lg, nv(lg)) == 1
-                    @test outdegree(lg, nv(lg)) == 0
-                end
+                @test all(outdegree(lg, v) == (v < n - 1 ? 1 : 0) for v in vertices(lg))
+                @test all(indegree(lg, v) == (v > 1 ? 1 : 0) for v in vertices(lg))
             end
         end
 
         @testset "Directed Star Graphs" begin
-            for n in 3:9
-                g = star_digraph(n)
-                lg = line_graph(g)
-                @test nv(lg) == n - 1
-                @test ne(lg) == 0
-            end
-
-            for n in 3:9
-                g = SimpleDiGraph(n)
-                for i in 2:n
-                    add_edge!(g, 1, i)
-                    add_edge!(g, i, 1)
-                end
-                lg = line_graph(g)
-                @test nv(lg) == 2*(n-1)
-                @test ne(lg) == (n-1) + (n-1)*(n-1)
+            for m in 0:4, n in 0:4
+                g = SimpleDiGraph(m + n + 1)
+                foreach(i -> add_edge!(g, i + 1, 1), 1:m)
+                foreach(j -> add_edge!(g, 1, j + 1 + m), 1:n)
+                lg = line_graph(g)  # checking if lg is the complete bipartite digraph
+                @test nv(lg) == m + n
+                @test ne(lg) == m * n
+                @test all(outdegree(lg, v) == 0 && indegree(lg, v) == m for v in 1:n)
+                @test all(
+                    outdegree(lg, v) == n && indegree(lg, v) == 0 for v in (n + 1):(n + m)
+                )
             end
         end
 
         @testset "Directed Self-loops" begin
-            g = SimpleDiGraph(2)
-            add_edge!(g, 1, 1)
-            add_edge!(g, 1, 2)
+            g = SimpleDiGraph(2, [[1, 2], Int[], Int[]], [[1], [1], Int[]])
             lg = line_graph(g)
             @test nv(lg) == 2
-            @test ne(lg) == 2
-            @test has_edge(lg, 1, 1)
+            @test ne(lg) == 1
             @test has_edge(lg, 1, 2)
-            @test !has_edge(lg, 2, 1)
-            @test !has_edge(lg, 2, 2)
-        end
-    end
-end
-
-@testset "Undirected Line Graph" begin
-    @testset "Undirected Cycle Graphs" begin
-        for n in 3:9
-            g = cycle_graph(n)
-            lg = line_graph(g)  # checking if lg is an n-cycle
-            @test nv(lg) == n
-            @test ne(lg) == n
-            @test is_connected(lg)
-            @test all(degree(lg, v) == 2 for v in vertices(lg))
-        end
-    end
-
-    @testset "Undirected Path Graphs" begin
-        for n in 2:9
-            g = path_graph(n)
-            lg = line_graph(g)  # checking if lg is an n-1-path
-            @test nv(lg) == n - 1
-            @test ne(lg) == n - 2
-            @test is_connected(lg)
-            @test all(degree(lg, v) <= 2 for v in vertices(lg))
-            @test any(degree(lg, v) == 1 for v in vertices(lg)) || n == 2 && ne(lg) == 0
         end
     end
-
-    @testset "Undirected Star Graphs" begin
-        for n in 3:9
-            g = star_graph(n)
-            lg = line_graph(g)  # checking if lg is a complete graph on n-1 vertices
-            @test nv(lg) == n - 1
-            @test ne(lg) == binomial(n - 1, 2)  # lg must be a complete graph
-        end
-    end
-
-    @testset "Undirected Self-loops" begin
-        g = SimpleGraph(2, [[2], [1, 2], Int[]])
-        lg = line_graph(g)
-        @test nv(lg) == 2  # only 2 edges (self-loop counts once)                                                                                                                                                                           
-        @test ne(lg) == 1  # only connection between edge 1-2 and self-loop 2-2                                                                                                                                                               
-    end
-
-    
 end