[LCHIB-641] if '%' is missing on Windows, suggest a likely cause of e…

launchable/utils/click.py

@@ -29,14 +29,20 @@ class PercentageType(ParamType):
 
     def convert(self, value: str, param: Optional[click.core.Parameter], ctx: Optional[click.core.Context]):
         try:
+            missing_percent = False
             if value.endswith('%'):
                 x = float(value[:-1]) / 100
                 if 0 <= x <= 100:
                     return x
+            else:
+                missing_percent = True
         except ValueError:
             pass
 
-        self.fail("Expected percentage like 50% but got '{}'".format(value), param, ctx)
+        msg = "Expected percentage like 50% but got '{}'".format(value)
+        if missing_percent and sys.platform.startswith("win"):
+            msg += " ('%' is a special character in batch files, so please write '50%%' to pass in '50%')"
+        self.fail(msg, param, ctx)
 
 
 class DurationType(ParamType):

tests/utils/test_click.py

@@ -1,4 +1,5 @@
 import datetime
+import sys
 from datetime import timezone
 from typing import Sequence, Tuple
 from unittest import TestCase
@@ -7,7 +8,51 @@
 from click.testing import CliRunner
 from dateutil.tz import tzlocal
 
-from launchable.utils.click import DATETIME_WITH_TZ, KEY_VALUE, convert_to_seconds
+from launchable.utils.click import DATETIME_WITH_TZ, KEY_VALUE, PercentageType, convert_to_seconds
+
+
+class PercentageTypeTest(TestCase):
+    ERROR_MSG = "Expected percentage like 50% but got"
+    WINDOWS_ERROR_MSG = "please write '50%%' to pass in '50%'"
+
+    def test_invalid_value_windows(self):
+        pct = PercentageType()
+        orig_platform = sys.platform
+        sys.platform = "win32"
+        try:
+            with self.assertRaises(click.BadParameter) as cm:
+                pct.convert("50", None, None)
+            msg = str(cm.exception)
+            self.assertIn(self.ERROR_MSG + " '50'", msg)
+            self.assertIn(self.WINDOWS_ERROR_MSG, msg)
+        finally:
+            sys.platform = orig_platform
+
+    def test_invalid_value_non_windows(self):
+        pct = PercentageType()
+        orig_platform = sys.platform
+        sys.platform = "linux"
+        try:
+            with self.assertRaises(click.BadParameter) as cm:
+                pct.convert("50", None, None)
+            msg = str(cm.exception)
+            self.assertIn(self.ERROR_MSG + " '50'", msg)
+            self.assertNotIn(self.WINDOWS_ERROR_MSG, msg)
+        finally:
+            sys.platform = orig_platform
+
+    def test_invalid_float(self):
+        pct = PercentageType()
+        with self.assertRaises(click.BadParameter) as cm:
+            pct.convert("abc%", None, None)
+        msg = str(cm.exception)
+        self.assertIn(self.ERROR_MSG + " 'abc%'", msg)
+
+    def test_valid(self):
+        pct = PercentageType()
+        self.assertEqual(pct.convert("50%", None, None), 0.5)
+        self.assertEqual(pct.convert("0%", None, None), 0.0)
+        self.assertEqual(pct.convert("100%", None, None), 1.0)
 
 
 class DurationTypeTest(TestCase):