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, 44 insertions, 0 deletions

diff --git a/python/tests/files/datacite/datacite_result_12.json b/python/tests/files/datacite/datacite_result_12.json
new file mode 100644
index 00000000..6b6cad4a
--- /dev/null
+++ b/python/tests/files/datacite/datacite_result_12.json
@@ -0,0 +1,44 @@
+{
+    "extra": {},
+    "title": "Anthropometric and Physiological Profile of Mixed Martial Art Athletes: A Brief Review",
+    "release_type": "article-journal",
+    "release_stage": "published",
+    "release_date": "2019-06-14",
+    "release_year": 2019,
+    "ext_ids": {
+        "doi": "10.5167/uzh-171449"
+    },
+    "publisher": "MDPI Publishing",
+    "contribs": [
+        {
+            "index": 0,
+            "raw_name": "Spanias, Charalampos",
+            "given_name": "Charalampos",
+            "surname": "Spanias",
+            "role": "author"
+        },
+        {
+            "index": 1,
+            "raw_name": "Nikolaidis, Pantelis T",
+            "given_name": "Pantelis T",
+            "surname": "Nikolaidis",
+            "role": "author"
+        },
+        {
+            "index": 2,
+            "raw_name": "Rosemann, Thomas",
+            "given_name": "Thomas",
+            "surname": "Rosemann",
+            "role": "author"
+        },
+        {
+            "index": 3,
+            "raw_name": "Knechtle, Beat",
+            "given_name": "Beat",
+            "surname": "Knechtle",
+            "role": "author"
+        }
+    ],
+    "refs": [],
+    "abstracts": []
+}
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