test_unit_parse_encrypt: skip double star test when running on mac

Since the included bash version on mac doesn't support double star.

test/test_unit_parse_encrypt.py

@@ -1,5 +1,7 @@
 """Unit tests: parse_encrypt"""
 
+import sys
+
 import pytest
 
 
@@ -123,16 +125,17 @@ def create_test_encrypt_data(paths):
     expected.add("ex ex/file4")
     expected.add("ex ex/file6.text")
 
-    # double star
-    edata += "doublestar/**/file*\n"
-    edata += "!**/file3\n"
-    paths.work.join("doublestar/a/b/file1").write("", ensure=True)
-    paths.work.join("doublestar/c/d/file2").write("", ensure=True)
-    paths.work.join("doublestar/e/f/file3").write("", ensure=True)
-    paths.work.join("doublestar/g/h/nomatch").write("", ensure=True)
-    expected.add("doublestar/a/b/file1")
-    expected.add("doublestar/c/d/file2")
-    # doublestar/e/f/file3 is excluded
+    # double star (not supported on bash 3 which is the default on macOS)
+    if sys.platform != "darwin":
+        edata += "doublestar/**/file*\n"
+        edata += "!**/file3\n"
+        paths.work.join("doublestar/a/b/file1").write("", ensure=True)
+        paths.work.join("doublestar/c/d/file2").write("", ensure=True)
+        paths.work.join("doublestar/e/f/file3").write("", ensure=True)
+        paths.work.join("doublestar/g/h/nomatch").write("", ensure=True)
+        expected.add("doublestar/a/b/file1")
+        expected.add("doublestar/c/d/file2")
+        # doublestar/e/f/file3 is excluded
 
     return edata, expected