Add RDF.PrefixMap.merge!/2

lib/rdf/prefix_map.ex

@@ -128,6 +128,17 @@ defmodule RDF.PrefixMap do
     (existing_namespace = Map.get(map, prefix)) && existing_namespace != namespace
   end
 
+  @doc """
+  Merges two `RDF.PrefixMap`s and raises an exception in error cases.
+  """
+  def merge!(prefix_map1, prefix_map2) do
+    with {:ok, new_prefix_map} <- merge(prefix_map1, prefix_map2) do
+      new_prefix_map
+    else
+      {:error, error} -> raise error
+    end
+  end
+
   @doc """
   Deletes a prefix mapping from the given `RDF.PrefixMap`..
   """

test/unit/prefix_map_test.exs

@@ -127,6 +127,19 @@ defmodule RDF.PrefixMapTest do
     end
   end
 
+  describe "merge!/2" do
+    test "when the prefix maps can be merged" do
+      other_prefix_map = PrefixMap.new(ex3: @ex_ns3)
+      assert PrefixMap.merge!(@example2, other_prefix_map) == @example3
+    end
+
+    test "when the prefix maps can not be merged" do
+      assert_raise RuntimeError, "conflicting prefix mappings: :ex2", fn ->
+        PrefixMap.merge!(@example2, ex2: @ex_ns3)
+      end
+    end
+  end
+
   describe "delete/2" do
     test "when a mapping of the given prefix exists" do
       assert PrefixMap.delete(@example2, :ex2) == @example1