Tests: Fix get_or_merge_testing_config cli tests

cli.main_build.execute (et al.) call the function with **args.__dict__
with args having default values (e.g., croot=None) via parse_args.

Signed-off-by: Marcel Bargull <marcel.bargull@udo.edu>

tests/cli/test_main_build.py

@@ -2,7 +2,6 @@
 # SPDX-License-Identifier: BSD-3-Clause
 import os
 import re
-import sys
 from pathlib import Path
 
 import pytest
@@ -104,8 +103,7 @@ def test_build_output_build_path(
     args = ["--output", testing_workdir]
     main_build.execute(args)
     test_path = os.path.join(
-        sys.prefix,
-        "conda-bld",
+        testing_config.croot,
         testing_config.host_subdir,
         "test_build_output_build_path-1.0-1.tar.bz2",
     )
@@ -124,9 +122,7 @@ def test_build_output_build_path_multiple_recipes(
 
     main_build.execute(args)
 
-    test_path = lambda pkg: os.path.join(
-        sys.prefix, "conda-bld", testing_config.host_subdir, pkg
-    )
+    test_path = lambda pkg: os.path.join(testing_config.croot, testing_config.host_subdir, pkg)
     test_paths = [
         test_path("test_build_output_build_path_multiple_recipes-1.0-1.tar.bz2"),
     ]

tests/conftest.py

@@ -118,11 +118,17 @@ def default_testing_config(testing_config, monkeypatch, request):
         return
 
     def get_or_merge_testing_config(config, variant=None, **kwargs):
-        merged_kwargs = {}
         if not config:
-            merged_kwargs.update(testing_config._testing_config_kwargs)
-        merged_kwargs.update(kwargs)
-        return _get_or_merge_config(config, variant, **merged_kwargs)
+            # If no existing config, override kwargs that are None with testing config defaults.
+            # (E.g., "croot" is None if called via "(..., *args.__dict__)" in cli.main_build.)
+            kwargs.update(
+                {
+                    key: value
+                    for key, value in testing_config._testing_config_kwargs.items()
+                    if kwargs.get(key) is None
+                }
+            )
+        return _get_or_merge_config(config, variant, **kwargs)
 
     monkeypatch.setattr(
         conda_build.config,