gnulib-tool.py: Implement --add-import --with-*-tests correctly

[Bruno Haible]

This patch fixes those unit tests that check the behaviour of
--with-*-tests options w.r.t. gnulib-cache.m4.

Now, all unit tests pass again.


2024-04-12  Bruno Haible  <bruno@clisp.org>

        gnulib-tool.py: Implement --add-import --with-*-tests correctly.
        * pygnulib/GLConfig.py (GLConfig.update): Use list-merging for the test
        categories.
        * pygnulib/GLImport.py (GLImport.__init__): Don't merge back those
        values which were already considered by taking the union.

diff --git a/pygnulib/GLConfig.py b/pygnulib/GLConfig.py
index 4e1eeb1375..9a4f4bfe68 100644
--- a/pygnulib/GLConfig.py
+++ b/pygnulib/GLConfig.py
@@ -290,7 +290,8 @@ class GLConfig:
                     if self.isdefault(key, dest):
                         value = src
                     else:  # if not self.isdefault(key, dest)
-                        if key in ['modules', 'avoids']:
+                        if key in ['modules', 'avoids',
+                                   'incl_test_categories', 
'excl_test_categories']:
                             value = sorted(set(src + dest))
                         else:
                             value = dest
diff --git a/pygnulib/GLImport.py b/pygnulib/GLImport.py
index 210768bd68..d45cf6b3ba 100644
--- a/pygnulib/GLImport.py
+++ b/pygnulib/GLImport.py
@@ -264,7 +264,8 @@ class GLImport:
             # Merge with the configuration from the command-line parameters;
             # they override the configuration found on disk.
             for key in config.keys():
-                if key not in ['modules', 'avoids']:
+                if key not in ['modules', 'avoids',
+                               'incl_test_categories', 'excl_test_categories']:
                     value = config[key]
                     if not config.isdefault(key, value):
                         self.config.update_key(config, key)