Test templates registries and resolve_template precedence

Covers the netlist-first precedence contract (names in both registries),
asc-only/netlist-only resolution, unknown -> None, and the deduped union
in all_template_names -- the lookup logic tune_circuit depends on.

tests/test_templates.py

@@ -0,0 +1,58 @@
+"""Tests for the circuit template registries and lookup helpers."""
+
+from mcltspice.templates import (
+    ASC_TEMPLATES,
+    NETLIST_TEMPLATES,
+    all_template_names,
+    resolve_template,
+)
+
+
+class TestRegistries:
+    def test_both_registries_populated(self):
+        assert len(NETLIST_TEMPLATES) == 15
+        assert len(ASC_TEMPLATES) == 15
+
+    def test_every_entry_has_required_keys(self):
+        for reg in (NETLIST_TEMPLATES, ASC_TEMPLATES):
+            for name, entry in reg.items():
+                assert callable(entry["func"]), name
+                assert isinstance(entry["description"], str) and entry["description"], name
+                assert isinstance(entry["params"], dict), name
+
+
+class TestResolveTemplate:
+    def test_netlist_first_precedence(self):
+        """A name in both registries resolves to its netlist form."""
+        assert "rc_lowpass" in NETLIST_TEMPLATES
+        assert "rc_lowpass" in ASC_TEMPLATES
+        entry, is_netlist = resolve_template("rc_lowpass")
+        assert is_netlist is True
+        assert entry is NETLIST_TEMPLATES["rc_lowpass"]
+
+    def test_asc_only_name(self):
+        """A name only in the asc registry resolves there, is_netlist False."""
+        assert "inverting_amp" in ASC_TEMPLATES
+        assert "inverting_amp" not in NETLIST_TEMPLATES
+        entry, is_netlist = resolve_template("inverting_amp")
+        assert is_netlist is False
+        assert entry is ASC_TEMPLATES["inverting_amp"]
+
+    def test_netlist_only_name(self):
+        assert "inverting_amplifier" in NETLIST_TEMPLATES
+        entry, is_netlist = resolve_template("inverting_amplifier")
+        assert is_netlist is True
+
+    def test_unknown_returns_none(self):
+        assert resolve_template("does_not_exist") is None
+
+
+class TestAllTemplateNames:
+    def test_is_sorted_union(self):
+        names = all_template_names()
+        expected = sorted(set(NETLIST_TEMPLATES) | set(ASC_TEMPLATES))
+        assert names == expected
+
+    def test_dedupes_overlapping_names(self):
+        # 15 + 15 with 9 shared names -> 21 unique
+        assert len(all_template_names()) == 21