Add some extra tests for good and bad cases.

src/briefcase/commands/new.py

@@ -166,7 +166,7 @@ def make_app_name(self, formal_name):
 
     def validate_formal_name(self, candidate):
         """Determine if the formal name is valid.
-        
+
         A formal name is valid if it contains at least one identifier character.
 
         :param candidate: The candidate name

src/briefcase/config.py

@@ -74,7 +74,7 @@ def make_class_name(formal_name):
     # If the first character isn't in the 'start' character set,
     # and it isn't already an underscore, prepend an underscore.
     if (
-        class_name != ""
+        class_name
         and unicodedata.category(class_name[0]) not in xid_start
         and class_name[0] != "_"
     ):

tests/commands/new/test_validate_formal_name.py

@@ -4,14 +4,23 @@
 @pytest.mark.parametrize(
     "name",
     [
+        # Various forms of capitalization and alphanumeric
+        "Hello World",
         "helloworld",
         "helloWorld",
         "hello42world",
         "42helloworld",
+        # Names that include punctuation
         "hello_world",
         "hello-world",
         "_helloworld",
         "/helloworld",
+        "Hello / World!",
+        # Internationalized names that can be unicode-simplified
+        "Hallo Vögel",
+        "Bonjour Garçon",
+        # Internationalized names that cannot be unicode-simplified
+        "你好 世界!",
     ],
 )
 def test_valid_formal_name(new_command, name):
@@ -22,6 +31,9 @@ def test_valid_formal_name(new_command, name):
 @pytest.mark.parametrize(
     "name",
     [
+        "",  # Empty
+        " ",  # Just a space
+        "\t",  # Other whitespace characters
         "/",  # Just a slash
         "'",
         "\\",