List the ions of the database utu.spectrum.ions() is given

utu/spectrum/_lines.py

@@ -41,6 +41,8 @@ def ions(
         worth including.
     kwargs
         Additional arguments passed to :class:`fiasco.Ion`.
+        If ``hdf5_dbase_root`` is among them, the ions are listed from that
+        database too.
 
     Notes
     -----
@@ -116,7 +118,10 @@ def _catalog(
     """
     result = {}
 
-    for name in fiasco.list_ions():
+    # the ions of the database they are read from, not of the default one
+    database = kwargs.get("hdf5_dbase_root")
+
+    for name in fiasco.list_ions(hdf5_dbase_root=database):
         try:
             ion = fiasco.Ion(name, 1 * u.MK, **kwargs)
 

utu/spectrum/_tests/test_lines.py

@@ -1,3 +1,5 @@
+import pathlib
+
 import astropy.units as u
 import fiasco
 import named_arrays as na
@@ -83,6 +85,22 @@ def test_ions(ions_window: list[str], ions_all: list[str]):
     assert len(ions_window) < len(ions_all)
 
 
+def test_ions_database(monkeypatch: pytest.MonkeyPatch, tmp_path: pathlib.Path):
+    """The ions are listed from the database they are read from."""
+    found = []
+
+    def list_ions(hdf5_dbase_root: object = None, sort: bool = True) -> list[str]:
+        """Record the database the ions are listed from, which has none."""
+        found.append(hdf5_dbase_root)
+        return []
+
+    monkeypatch.setattr(fiasco, "list_ions", list_ions)
+    database = tmp_path / "chianti.h5"
+
+    assert utu.spectrum.ions(hdf5_dbase_root=database) == []
+    assert found == [database]
+
+
 @needs_database
 def test_contribution_function(proton_electron_ratio: u.Quantity):
     ion = fiasco.Ion("O 5", temperature.ndarray)