core: RDF.Vocabulary.Namespaces can be constructed from NQuad files

lib/rdf/vocabulary_namespace.ex

@@ -462,7 +462,14 @@ defmodule RDF.Vocabulary.Namespace do
   end
 
   defp load_file(file) do
-    RDF.NTriples.read_file!(file)  # TODO: support other formats
+    # TODO: support other formats
+    cond do
+      String.ends_with?(file, ".nt") -> RDF.NTriples.read_file!(file)
+      String.ends_with?(file, ".nq") -> RDF.NQuads.read_file!(file)
+      true ->
+        raise ArgumentError,
+          "unsupported file type for #{file}: vocabulary namespaces can currently be created from NTriple and NQuad files"
+    end
   end
 
   defp rdf_data_env do

test/data/vocab_ns_example.nq

@@ -0,0 +1,2 @@
+<http://example.com/from_nquads/foo> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
+<http://example.com/from_nquads/Bar> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2000/01/rdf-schema#Resource> <http://example.com/from_nquads/Graph>.

test/unit/vocabulary_namespace_test.exs

@@ -35,7 +35,11 @@ defmodule RDF.Vocabulary.NamespaceTest do
 
     defvocab ExampleFromNTriplesFile,
       base_uri: "http://example.com/from_ntriples/",
-      file: "test/data/vocab_ns_example2.nt"
+      file: "test/data/vocab_ns_example.nt"
+
+    defvocab ExampleFromNQuadsFile,
+      base_uri: "http://example.com/from_nquads/",
+      file: "test/data/vocab_ns_example.nq"
 
     defvocab StrictExampleFromTerms,
       base_uri: "http://example.com/strict_from_terms#",
@@ -351,12 +355,22 @@ defmodule RDF.Vocabulary.NamespaceTest do
     assert RDF.uri(Example1.foo) in Example1.__uris__
     assert RDF.uri(Example1.Bar) in Example1.__uris__
 
-    alias TestNS.StrictExampleFromAliasedTerms, as: Example2
-    assert length(Example2.__uris__) == 4
-    assert RDF.uri(Example2.Term1) in Example2.__uris__
-    assert RDF.uri(Example2.term2) in Example2.__uris__
-    assert RDF.uri(Example2.Term3) in Example2.__uris__
-    assert RDF.uri(Example2.term4) in Example2.__uris__
+    alias TestNS.ExampleFromNTriplesFile, as: Example2
+    assert length(Example2.__uris__) == 2
+    assert RDF.uri(Example2.foo) in Example2.__uris__
+    assert RDF.uri(Example2.Bar) in Example2.__uris__
+
+    alias TestNS.ExampleFromNQuadsFile, as: Example3
+    assert length(Example3.__uris__) == 2
+    assert RDF.uri(Example3.foo) in Example3.__uris__
+    assert RDF.uri(Example3.Bar) in Example3.__uris__
+
+    alias TestNS.StrictExampleFromAliasedTerms, as: Example4
+    assert length(Example4.__uris__) == 4
+    assert RDF.uri(Example4.Term1) in Example4.__uris__
+    assert RDF.uri(Example4.term2) in Example4.__uris__
+    assert RDF.uri(Example4.Term3) in Example4.__uris__
+    assert RDF.uri(Example4.term4) in Example4.__uris__
   end