Add RDF.Diff.empty?/1

lib/rdf/diff.ex

@@ -150,6 +150,15 @@ defmodule RDF.Diff do
     )
   end
 
+  @doc """
+  Determines if a diff is empty.
+
+  A `RDF.Diff` is empty, if its `additions` and `deletions` graphs are empty.
+  """
+  def empty?(%__MODULE__{} = diff) do
+    Enum.empty?(diff.additions) and Enum.empty?(diff.deletions)
+  end
+
   @doc """
   Applies a diff to a `RDF.Graph` or `RDF.Description` by deleting the `deletions` and adding the `additions` of the `diff`.
 

test/unit/diff_test.exs

@@ -198,6 +198,14 @@ defmodule RDF.DiffTest do
              )
   end
 
+  test "empty?/1" do
+    assert Diff.empty?(Diff.new()) == true
+    assert Diff.empty?(Diff.new(additions: EX.p(EX.S, EX.O),
+                                deletions: EX.p(EX.S, EX.O))) == false
+    assert Diff.empty?(Diff.new(additions: EX.p(EX.S, EX.O))) == false
+    assert Diff.empty?(Diff.new(deletions: EX.p(EX.S, EX.O))) == false
+  end
+
   describe "apply/2" do
     test "on a graph" do
       assert Diff.new(