[Pather] make two-L path planning atomic (don't error out with only one half drawn)

masque/test/test_pather_api.py

@@ -1,7 +1,9 @@
+import pytest
 import numpy
 from numpy import pi
 from masque import Pather, RenderPather, Library, Pattern, Port
 from masque.builder.tools import PathTool
+from masque.error import BuildError
 
 def test_pather_trace_basic() -> None:
     lib = Library()
@@ -240,3 +242,31 @@ def test_pather_trace_into() -> None:
     assert numpy.allclose(p.pattern.ports['G'].offset, (-10000, 2000))
     assert p.pattern.ports['G'].rotation is not None
     assert numpy.isclose(p.pattern.ports['G'].rotation, pi)
+
+
+def test_pather_jog_failed_fallback_is_atomic() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=2, ptype='wire')
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    with pytest.raises(BuildError, match='shorter than required bend'):
+        p.jog('A', 1.5, length=5)
+
+    assert numpy.allclose(p.pattern.ports['A'].offset, (0, 0))
+    assert p.pattern.ports['A'].rotation == 0
+    assert len(p.paths['A']) == 0
+
+
+def test_pather_uturn_failed_fallback_is_atomic() -> None:
+    lib = Library()
+    tool = PathTool(layer='M1', width=2, ptype='wire')
+    p = Pather(lib, tools=tool)
+    p.pattern.ports['A'] = Port((0, 0), rotation=0, ptype='wire')
+
+    with pytest.raises(BuildError, match='shorter than required bend'):
+        p.uturn('A', 1.5, length=0)
+
+    assert numpy.allclose(p.pattern.ports['A'].offset, (0, 0))
+    assert p.pattern.ports['A'].rotation == 0
+    assert len(p.paths['A']) == 0