Fix testcase

Author: MomIsBestFriend

pandas/_libs/tslibs/nattype.pyx

@@ -467,7 +467,14 @@ class NaTType(_NaT):
         Return a new Timestamp representing UTC day and time.
         """
     )
+    fromisocalendar = _make_error_func('fromisocalendar',  # noqa:E128
+        """
+        Timestamp.fromisocalendar(year, week, day)
 
+        Return a new Timestamp corresponding to the
+        ISO calendar date specified by year, week and day.
+        """
+    )
     timestamp = _make_error_func('timestamp',  # noqa:E128
         """Return POSIX timestamp as float.""")
 

pandas/_libs/tslibs/timestamps.pyx

@@ -344,6 +344,13 @@ class Timestamp(_Timestamp):
         Return a new Timestamp corresponding to the
         ISO calendar date specified by year, week and day.
         """
+        import pandas.compact as compact
+
+        if not compact.PY38:
+            raise NotImplementedError(
+                "'fromisocalendar' is not supported for versions earlier to 3.8"
+            )
+
         return cls(datetime.fromisocalendar(year, week, day))
 
     def __new__(cls, object ts_input=_no_input,

pandas/tests/scalar/test_nat.py

@@ -297,6 +297,7 @@ def test_overlap_public_nat_methods(klass, expected):
     # "fromisoformat" was introduced in 3.7
     if klass is Timestamp and not compat.PY37:
         expected.remove("fromisoformat")
+    # "fromisocalendar" was introduced in 3.8
     if klass is Timestamp and not compat.PY38:
         expected.remove("fromisocalendar")