improve test coverage

Author: scivision

test/TestFilename.m

@@ -3,7 +3,7 @@
 properties (TestParameter)
 p = init_p()
 e = {'/a/b/c/', "a/b/c/"}
-backend = {'pattern', 'regexp'}
+backend = init_backend()
 end
 
 methods(TestClassSetup)
@@ -51,3 +51,16 @@ function test_filename_array(tc, backend)
 end
 
 end
+
+
+function backend = init_backend()
+
+backend = {'regexp'};
+
+try %#ok<TRYNC>
+  if ~isMATLABReleaseOlderThan('R2020b')
+    backend{end+1} = 'pattern';
+  end
+end
+
+end

test/TestStem.m

@@ -14,7 +14,6 @@
 {"", ""}, ...
 {'', ""}
 }
-
 end
 
 methods(TestClassSetup)