Add test case for compaction with @vocab

tests/test_jsonld.py

@@ -969,3 +969,38 @@ def test_no_initial_context_and_with_skip_expand_does_not_drop_property_when_arr
         compacted = jsonld.compact(input, {"@vocab": "http://example.org#"}, {"skipExpansion": True})
         expected = {"@context": {"@vocab": "http://example.org#"}, "name": "Bob"}
         assert compacted == expected
+
+    # Issue 83
+    def test_with_vocab_no_id(self):
+        """
+        Compacting with @vocab should not compact a plain string value
+        """
+        ctx = {'@vocab': 'http://ex.org/#', 'path': {'@type': '@id'}}
+        input = {
+            'http://ex.org/#path': 'http://ex.org/#shortname',
+        }
+        expected = {
+            "@context": {"@vocab": "http://ex.org/#", "path": {"@type": "@id"}},
+            "http://ex.org/#path": "http://ex.org/#shortname",
+        }
+
+        compacted = jsonld.compact(input, ctx)
+
+        assert compacted == expected
+
+    def test_with_vocab_with_id(self):
+        """
+        Compacting with @vocab should compact an @id value
+        """
+        ctx = {'@vocab': 'http://ex.org/#', 'path': {'@type': '@id'}}
+        input = {
+            'http://ex.org/#path': {'@id': 'http://ex.org/#shortname'},
+        }
+        expected = {
+            "@context": {"@vocab": "http://ex.org/#", "path": {"@type": "@id"}},
+            "path": "http://ex.org/#shortname",
+        }
+
+        compacted = jsonld.compact(input, ctx)
+
+        assert compacted == expected