Consider SHELL env var (#3997)

Author: Hind-M

libmamba/src/core/shell_init.cpp

@@ -97,6 +97,14 @@ namespace mamba
         {
             return "fish";
         }
+
+        // Get `SHELL` environment variable if set
+        // Standard values are assumed to be `/bin/{shell_type}` or `/usr/bin/{shell_type}`
+        if (util::get_env("SHELL").has_value())
+        {
+            return util::split(util::get_env("SHELL").value(), "/").back();
+        }
+
         return "";
     }
 

libmamba/tests/src/util/test_string.cpp

@@ -460,6 +460,10 @@ namespace
             std::vector<std::string> v21 = { "conda-forge/linux64:", "xtensor==0.12.3" };
 
             REQUIRE(rsplit("conda-forge/linux64::xtensor==0.12.3", ":", 1) == v21);
+
+            std::vector<std::string> es3 = { "" };
+            REQUIRE(split(es3[0], ".") == es3);
+            REQUIRE(rsplit(es3[0], ".") == es3);
         }
 
         TEST_CASE("join")

micromamba/tests/test_shell.py

@@ -225,6 +225,14 @@ def test_init(tmp_home, tmp_root_prefix, shell_type, prefix_selector, multiple_t
         assert (tmp_root_prefix / "condabin").is_dir()
 
 
+def test_shell_init_with_env_var(tmp_home, tmp_root_prefix):
+    skip_if_shell_incompat("bash")
+    umamba_cmd = helpers.get_umamba()
+    res = helpers.umamba_run("sh", "-c", f"export SHELL=/bin/bash; {umamba_cmd} shell init")
+    assert res
+    assert (tmp_root_prefix / "etc" / "profile.d").is_dir()
+
+
 def test_dash(tmp_home, tmp_root_prefix):
     skip_if_shell_incompat("dash")
     umamba = helpers.get_umamba()