datacite: add conversion fixtures

The `test_datacite_conversions` function will compare an input
(datacite) document to an expected output (release entity as JSON). This
way, it should not be too hard to add more cases by adding: input,
output - and by increasing the counter in the range loop within the
test.

To view input and result side by side with vim, change into the test
directory and run:

    tests/files/datacite $ ./caseview.sh 18

1 files changed, 87 insertions, 0 deletions

diff --git a/python/tests/files/datacite/datacite_result_00.json b/python/tests/files/datacite/datacite_result_00.json
new file mode 100644
index 00000000..085e23f3
--- /dev/null
+++ b/python/tests/files/datacite/datacite_result_00.json
@@ -0,0 +1,87 @@
+{
+    "extra": {
+        "container_name": "Journal of Chemical Crystallography",
+        "datacite": {
+            "license": [
+                {
+                    "rightsUri": "http://www.springer.com/tdm"
+                }
+            ],
+            "relations": [
+                {
+                    "relationType": "IsPartOf",
+                    "relatedIdentifier": "1074-1542",
+                    "resourceTypeGeneral": "Collection",
+                    "relatedIdentifierType": "ISSN"
+                }
+            ]
+        }
+    },
+    "title": "Synthesis and Crystal Structure of a Compound with Two Conformational Isomers: N-(2-methylbenzoyl)-N\u2032-(4-nitrophenyl)thiourea",
+    "release_type": "article-journal",
+    "release_stage": "published",
+    "release_date": "2019-05-31",
+    "release_year": 2019,
+    "ext_ids": {
+        "doi": "10.1007/s10870-008-9413-z"
+    },
+    "volume": "38",
+    "issue": "12",
+    "pages": "927-930",
+    "publisher": "Springer Science and Business Media LLC",
+    "contribs": [
+        {
+            "index": 0,
+            "raw_name": "Li, Qian-Jin",
+            "given_name": "Qian-Jin",
+            "surname": "Li",
+            "role": "author"
+        },
+        {
+            "index": 1,
+            "raw_name": "Yang, Chun-Long",
+            "given_name": "Chun-Long",
+            "surname": "Yang",
+            "role": "author"
+        }
+    ],
+    "refs": [
+        {
+            "index": 0,
+            "extra": {
+                "doi": "10.1016/j.bmcl.2005.09.033"
+            }
+        },
+        {
+            "index": 1,
+            "extra": {
+                "doi": "10.1016/s0022-1139(02)00330-5"
+            }
+        },
+        {
+            "index": 2,
+            "extra": {
+                "doi": "10.1016/s0010-8545(01)00337-x"
+            }
+        },
+        {
+            "index": 3,
+            "extra": {
+                "doi": "10.1016/j.tetlet.2005.06.135"
+            }
+        },
+        {
+            "index": 4,
+            "extra": {
+                "doi": "10.1039/p298700000s1"
+            }
+        },
+        {
+            "index": 5,
+            "extra": {
+                "doi": "10.1002/anie.199515551"
+            }
+        }
+    ],
+    "abstracts": []
+}
\ No newline at end of file