fix: Adapt root prefix' precedence for envs_dirs

libmamba/include/mamba/api/configuration_impl.hpp

@@ -83,7 +83,7 @@ namespace mamba
         {
             static std::vector<std::string> default_value(const std::vector<T>& init)
             {
-                return std::vector<std::string>(init.size(), "default");
+                return std::vector<std::string>(std::max<size_t>(1, init.size()), "default");
             };
 
             static void merge(

libmamba/src/core/context.cpp

@@ -181,7 +181,7 @@ namespace mamba
         prefix_params.root_prefix = detail::get_root_prefix();
         prefix_params.conda_prefix = prefix_params.root_prefix;
 
-        envs_dirs = { prefix_params.root_prefix / "envs" };
+        envs_dirs = {};
         pkgs_dirs = { prefix_params.root_prefix / "pkgs",
                       fs::u8path("~") / ".mamba" / "pkgs"
 #ifdef _WIN32

micromamba/tests/test_create.py

@@ -253,6 +253,7 @@ def test_env_logging_overhead_regression(tmp_home, tmp_root_prefix, tmp_path):
     "similar_non_canonical,non_canonical_position",
     ((False, None), (True, "append"), (True, "prepend")),
 )
+@pytest.mark.parametrize("root_prefix_env_exists", (False, True))
 def test_target_prefix(
     tmp_home,
     tmp_root_prefix,
@@ -266,6 +267,7 @@ def test_target_prefix(
     current_target_prefix_fallback,
     similar_non_canonical,
     non_canonical_position,
+    root_prefix_env_exists,
 ):
     cmd = []
 
@@ -277,6 +279,9 @@ def test_target_prefix(
     else:
         root_prefix = Path(os.environ["MAMBA_ROOT_PREFIX"])
 
+    if root_prefix_env_exists:
+        os.mkdir(Path(os.environ["MAMBA_ROOT_PREFIX"]) / "envs")
+
     env_prefix = tmp_path / "myenv"
 
     if target_is_root:
@@ -661,6 +666,39 @@ def test_create_envs_dirs(tmp_root_prefix: Path, tmp_path: Path):
     assert (tmp_path / env_name / "conda-meta" / "history").exists()
 
 
+@pytest.mark.parametrize("cli_root_prefix", (False, True))
+@pytest.mark.parametrize("user_envs_dirs", (False, True))
+def test_root_prefix_precedence(monkeypatch, tmp_path, user_envs_dirs, cli_root_prefix):
+    """Test for root prefix precedence"""
+
+    envroot = tmp_path / "envroot"
+    cliroot = tmp_path / "cliroot"
+    userenv = tmp_path / "userenv" / "envs"
+
+    map(lambda p: os.makedirs(p), (envroot, cliroot, userenv))
+
+    monkeypatch.setenv("MAMBA_ROOT_PREFIX", str(envroot))
+    cmd = ["mamba", "create", "-n", "foo", "--print-config-only", "--debug"]
+
+    if cli_root_prefix:
+        cmd += ["-r", cliroot]
+
+    if user_envs_dirs:
+        monkeypatch.setenv("CONDA_ENVS_DIRS", str(userenv))
+
+    res = helpers.create(*cmd)
+    envs_dirs = res["envs_dirs"]
+
+    if user_envs_dirs:
+        assert envs_dirs[0] == str(userenv)
+        envs_dirs = envs_dirs[1:]
+
+    if cli_root_prefix:
+        assert envs_dirs[0] == str(cliroot / "envs")
+    else:
+        assert envs_dirs[0] == str(envroot / "envs")
+
+
 @pytest.mark.skipif(
     helpers.dry_run_tests is helpers.DryRun.ULTRA_DRY,
     reason="Running only ultra-dry tests",