Use a paired RMG-database worktree when one exists

rmgpy/__init__.py

@@ -139,14 +139,46 @@ def load(self, path=None):
                     self["test_data.directory"] = value
                     self.sources["test_data.directory"] = "from {0}".format(self.filename)
 
+    @staticmethod
+    def default_database_directory(rmg_py_dir):
+        """
+        Return the default database directory for the RMG-Py checkout at
+        `rmg_py_dir`, along with a string saying where it came from.
+
+        If the checkout is a worktree named ``RMG-Py-<suffix>`` and a matching
+        ``RMG-database-<suffix>`` sits beside it, that paired database is used.
+        This lets several RMG-Py worktrees each use their own database
+        worktree, rather than all of them sharing the single ``RMG-database``
+        next door.
+
+        Otherwise the historical default is returned unchanged: the
+        ``RMG-database`` directory alongside the RMG-Py checkout.
+        """
+        parent_dir, checkout_name = os.path.split(rmg_py_dir)
+        prefix = "RMG-Py-"
+        if checkout_name.startswith(prefix):
+            paired = os.path.realpath(
+                os.path.join(parent_dir, "RMG-database-" + checkout_name[len(prefix):], "input")
+            )
+            if os.path.isdir(paired):
+                return paired, "Default, paired RMG-database worktree beside this RMG-Py worktree"
+
+        return (
+            os.path.realpath(os.path.join(rmg_py_dir, "..", "RMG-database", "input")),
+            "Default, relative to RMG-Py source code",
+        )
+
     def reset(self):
         """
         Reset all settings to their default values.
         """
         self.filename = None
         rmgpy_module_dir = os.path.abspath(os.path.dirname(__file__))
-        self["database.directory"] = os.path.realpath(os.path.join(rmgpy_module_dir, "..", "..", "RMG-database", "input"))
-        self.sources["database.directory"] = "Default, relative to RMG-Py source code"
+        database_dir, database_source = self.default_database_directory(
+            os.path.abspath(os.path.join(rmgpy_module_dir, ".."))
+        )
+        self["database.directory"] = database_dir
+        self.sources["database.directory"] = database_source
         self["test_data.directory"] = os.path.realpath(os.path.join(rmgpy_module_dir, "..", "test", "rmgpy", "test_data"))
         self.sources["test_data.directory"] = "Default, relative to RMG-Py source code"
 

test/rmgpy/settingsTest.py

@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+
+###############################################################################
+#                                                                             #
+# RMG - Reaction Mechanism Generator                                          #
+#                                                                             #
+# Copyright (c) 2002-2026 Prof. William H. Green (whgreen@mit.edu),           #
+# Prof. Richard H. West (r.west@neu.edu) and the RMG Team (rmg_dev@mit.edu)   #
+#                                                                             #
+# Permission is hereby granted, free of charge, to any person obtaining a     #
+# copy of this software and associated documentation files (the 'Software'),  #
+# to deal in the Software without restriction, including without limitation   #
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,    #
+# and/or sell copies of the Software, and to permit persons to whom the       #
+# Software is furnished to do so, subject to the following conditions:        #
+#                                                                             #
+# The above copyright notice and this permission notice shall be included in  #
+# all copies or substantial portions of the Software.                         #
+#                                                                             #
+# THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  #
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    #
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE #
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      #
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     #
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         #
+# DEALINGS IN THE SOFTWARE.                                                   #
+#                                                                             #
+###############################################################################
+
+"""
+This script contains unit tests of the :mod:`rmgpy` settings object.
+"""
+
+import os
+
+from rmgpy import Settings
+
+
+class TestDefaultDatabaseDirectory:
+    """
+    Tests for how the default database directory is chosen when no rmgrc
+    supplies one.
+    """
+
+    def test_paired_database_worktree_is_used(self, tmp_path):
+        """
+        A checkout named RMG-Py-<suffix> uses RMG-database-<suffix> beside it.
+        """
+        (tmp_path / "RMG-Py-feature").mkdir()
+        (tmp_path / "RMG-database-feature" / "input").mkdir(parents=True)
+
+        directory, source = Settings.default_database_directory(str(tmp_path / "RMG-Py-feature"))
+
+        assert directory == os.path.realpath(str(tmp_path / "RMG-database-feature" / "input"))
+        assert "paired" in source
+
+    def test_falls_back_when_the_paired_worktree_is_absent(self, tmp_path):
+        """
+        The suffix alone is not enough: with no RMG-database-<suffix> on disk,
+        the historical default is used, so an unpaired worktree is unaffected.
+        """
+        (tmp_path / "RMG-Py-feature").mkdir()
+        (tmp_path / "RMG-database" / "input").mkdir(parents=True)
+
+        directory, source = Settings.default_database_directory(str(tmp_path / "RMG-Py-feature"))
+
+        assert directory == os.path.realpath(str(tmp_path / "RMG-database" / "input"))
+        assert source == "Default, relative to RMG-Py source code"
+
+    def test_plain_checkout_name_is_unaffected(self, tmp_path):
+        """
+        An ordinary RMG-Py checkout keeps the behaviour it has always had,
+        even when a similarly named database directory happens to be present.
+        """
+        (tmp_path / "RMG-Py").mkdir()
+        (tmp_path / "RMG-database" / "input").mkdir(parents=True)
+
+        directory, source = Settings.default_database_directory(str(tmp_path / "RMG-Py"))
+
+        assert directory == os.path.realpath(str(tmp_path / "RMG-database" / "input"))
+        assert source == "Default, relative to RMG-Py source code"