You can now choose both input and output units for imperial formatting

src/ifcopenshell-python/test/util/test_selector.py

@@ -45,7 +45,8 @@ class TestFormat():
         assert subject.format('imperial_length(3.123, 1)') == "3' - 1\""
         assert subject.format('imperial_length(3.123, 2)') == "3' - 1 1/2\""
         assert subject.format('imperial_length(\"3.123\", 2)') == "3' - 1 1/2\""
-        assert subject.format('imperial_length(\"123.123\", 2, \"inch\")') == "10' - 3\""
+        assert subject.format('imperial_length(\"123.123\", 2, \"inch\", \"foot\")') == "10' - 3\""
+        assert subject.format('imperial_length(\"123.123\", 2, \"inch\", \"inch\")') == "123\""
 
 
 class TestGetElementValue(test.bootstrap.IFC4):

src/ifcopenshell-python/test/util/test_unit.py

@@ -0,0 +1,59 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2023 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import pytest
+import test.bootstrap
+import ifcopenshell.api
+import ifcopenshell.util.unit as subject
+
+
+class TestFormatLength(test.bootstrap.IFC4):
+    def test_run(self):
+        assert subject.format_length(1, 1, decimal_places=0, unit_system="metric") == "1"
+        assert subject.format_length(1, 1, decimal_places=2, unit_system="metric") == "1.00"
+        assert subject.format_length(3, 5, decimal_places=2, unit_system="metric") == "5.00"
+        assert subject.format_length(3.123, 0.01, decimal_places=2, unit_system="metric") == "3.12"
+
+        assert subject.format_length(3, 1, unit_system="imperial", input_unit="foot") == "3'"
+        assert subject.format_length(3.5, 1, unit_system="imperial", input_unit="foot") == "3' - 6\""
+        assert subject.format_length(3.123, 1, unit_system="imperial", input_unit="foot") == "3' - 1\""
+        assert subject.format_length(3.123, 2, unit_system="imperial", input_unit="foot") == "3' - 1 1/2\""
+        assert subject.format_length(3.123, 4, unit_system="imperial", input_unit="foot") == "3' - 1 1/2\""
+        assert subject.format_length(3.123, 32, unit_system="imperial", input_unit="foot") == "3' - 1 15/32\""
+        assert subject.format_length(24, 1, unit_system="imperial", input_unit="inch") == "2'"
+        assert subject.format_length(25.23, 1, unit_system="imperial", input_unit="inch") == "2' - 1\""
+        assert subject.format_length(25.23, 4, unit_system="imperial", input_unit="inch") == "2' - 1 1/4\""
+
+        assert subject.format_length(3, 1, unit_system="imperial", input_unit="foot", output_unit="inch") == '36"'
+        assert subject.format_length(3.5, 1, unit_system="imperial", input_unit="foot", output_unit="inch") == '42"'
+        assert subject.format_length(3.123, 1, unit_system="imperial", input_unit="foot", output_unit="inch") == '37"'
+        assert (
+            subject.format_length(3.123, 2, unit_system="imperial", input_unit="foot", output_unit="inch") == '37 1/2"'
+        )
+        assert (
+            subject.format_length(3.123, 4, unit_system="imperial", input_unit="foot", output_unit="inch") == '37 1/2"'
+        )
+        assert (
+            subject.format_length(3.123, 32, unit_system="imperial", input_unit="foot", output_unit="inch")
+            == '37 15/32"'
+        )
+        assert subject.format_length(24, 1, unit_system="imperial", input_unit="inch", output_unit="inch") == '24"'
+        assert subject.format_length(25.23, 1, unit_system="imperial", input_unit="inch", output_unit="inch") == '25"'
+        assert (
+            subject.format_length(25.23, 4, unit_system="imperial", input_unit="inch", output_unit="inch") == '25 1/4"'
+        )