test(apiutils): added a unittest for describe_diff function

tox.ini

@@ -17,6 +17,6 @@ max-line-length=100
 [pytest]
 testpaths = unittests
 xfail_strict = True
-addopts = -x -vv --cov=caosdb
+addopts = -x -vv --cov=linkahead
 pythonpath = src
 

unittests/test_apiutils.py

 #
 # This file is a part of the LinkAhead Project.
 #
+# Copyright (C) 2024 Alexander Schlemmer <a.schlemmer@indiscale.com>
 # Copyright (C) 2020 Timm Fitschen <t.fitschen@indiscale.com>
 # Copyright (C) 2022 Florian Spreckelsen <f.spreckelsen@indiscale.com>
 # Copyright (C) 2022 Daniel Hornung <d.hornung@indiscale.com>
@@ -31,7 +32,8 @@ import linkahead.apiutils
 import pytest
 from linkahead.apiutils import (EntityMergeConflictError, apply_to_ids,
                                 compare_entities, create_id_query, empty_diff,
-                                merge_entities, resolve_reference)
+                                merge_entities, resolve_reference,
+                                describe_diff)
 from linkahead.common.models import SPECIAL_ATTRIBUTES
 
 
@@ -627,3 +629,46 @@ def test_merge_id_with_resolved_entity():
     merge_entities(recA, recB, merge_id_with_resolved_entity=True)
     assert recA.get_property(rtname).value == [ref_id, ref_id*2]
     assert recA.get_property(rtname).value == recB.get_property(rtname).value
+
+
+def test_describe_diff():
+    recA = db.Record()
+    recA.add_property(name="propA", value=2)
+    recA.add_property(name="propB", value=2)
+    recA.add_property(name="propD", value=-273, unit="K")
+
+    recB = db.Record()
+    recB.add_property(name="propA", value=2)
+    recB.add_property(name="propB", value=12)
+    recB.add_property(name="propC", value="cool 17")
+    recB.add_property(name="propD", value=-273, unit="°C")
+
+    diff = compare_entities(recA, recB)
+    diffout = describe_diff(*diff)
+
+    assert diffout.startswith("## Difference between the old version and the new version of None")
+
+    # The output of the describe_diff function is currently not ordered (e.g. by name of the property)
+    # so we cannot just compare a well-defined output string.
+
+    assert "it does not exist in the old version:" in diffout
+    assert "old version: {'value': 2}" in diffout
+    assert "new version: {'value': 12}" in diffout
+
+    assert "old version: {'unit': 'K'}" in diffout
+    assert "new version: {'unit': '°C'}" in diffout
+
+    diffout = describe_diff(*diff, name="Entity")
+    assert diffout.startswith("## Difference between the old version and the new version of Entity")
+
+    diffout = describe_diff(*diff, label_old="recA", label_new="recB")
+    assert "recA: {'value': 2}" in diffout
+    assert "recB: {'value': 12}" in diffout
+
+    assert "recA: {'unit': 'K'}" in diffout
+    assert "recB: {'unit': '°C'}" in diffout
+
+    assert "it does not exist in the recA:" in diffout
+
+    assert "old" not in diffout
+    assert "new" not in diffout