Fixed #960

- Handles unit in to_compact.
- Use same function infer_base_unit on Quantity based on input unit.
- Add unit test in test_issues.py

2 files changed, 7 insertions, 0 deletions

diff --git a/pint/quantity.py b/pint/quantity.py
index 09f7aed..051fc84 100644
--- a/pint/quantity.py
+++ b/pint/quantity.py
@@ -689,6 +689,8 @@ class Quantity(PrettyIPython, SharedRegistryObject):
 
         if unit is None:
             unit = infer_base_unit(self)
+        else:
+            unit = infer_base_unit(self.__class__(1, unit))
 
         q_base = self.to(unit)
 
diff --git a/pint/testsuite/test_issues.py b/pint/testsuite/test_issues.py
index cc04e9f..5f42717 100644
--- a/pint/testsuite/test_issues.py
+++ b/pint/testsuite/test_issues.py
@@ -710,6 +710,11 @@ class TestIssues(QuantityTestCase):
         with self.assertRaises(AttributeError):
             one_blank = 1 * ureg._  # noqa: F841
 
+    def test_issue960(self):
+        q = (1 * ureg.nanometer).to_compact("micrometer")
+        assert q.units == ureg.nanometer
+        assert q.magnitude == 1
+
 
 try: