Human: Fix num2si dropping SI prefix for values in [1, 1000]

'num2si()' had an early-return shortcut for values already in [1, 1000)
that returned '{value}{base_unit}', discarding the SI prefix parsed from
the unit string. For example, 444.584 with unit "us" (sipfx="u",
base_unit="s") was returned as "444.58s" instead of "444.58us".

The early return is only valid when no SI prefix is present, i.e. the
value is already expressed in base units. Add 'not sipfx' to the
condition so prefixed units fall through to the full scaling logic.

Add test cases to 'test_num2si()' covering values in [1, 1000) with
SI-prefixed units (us, ms, mW).

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

Author: dedekind

CHANGELOG.md

@@ -5,6 +5,8 @@ Versioning practices: [Semantic Versioning](https://semver.org/spec/v2.0.0.html)
 
 ## [ADD NEW VERSION HERE] - ADD DATE HERE
 ### Fixed
+ - Fix 'num2si()' function, which lead to incorrect units conversion in some
+   cases.
 ### Added
 ### Removed
 ### Changed

pepclibs/helperlibs/Human.py

@@ -206,7 +206,8 @@ def num2si(value: int | float,
     sipfx, base_unit = separate_si_prefix(unit)
     value = float(value)
 
-    if abs(value) >= 1 and abs(value) < 1000:
+    # No scaling is needed for values in [1, 1000) with no SI prefix.
+    if not sipfx and abs(value) >= 1 and abs(value) < 1000:
         result = f"{value:.{decp}f}"
         if strip_zeroes and "." in result:
             result = result.rstrip("0").rstrip(".")

tests/test_human.py

@@ -198,6 +198,25 @@ class _Num2SiTestDataType(TypedDict, total=False):
      "unit": "W", "decp": 0, "sep": " ", "strip_zeroes": False, "result": "2 EW"},
     {"value": 1999 * 1000 * 1000 * 1000 * 1000 * 1000,
      "unit": "MW", "decp": 0, "sep": " ", "strip_zeroes": False, "result": "1999000 EW"},
+    # Values in [1, 1000) with an SI-prefixed unit must preserve the prefix.
+    {"value": 444.584,
+     "unit": "us", "decp": 2, "sep": None, "strip_zeroes": False, "result": "444.58us"},
+    {"value": 1.0,
+     "unit": "us", "decp": 2, "sep": None, "strip_zeroes": False, "result": "1.00us"},
+    {"value": 999.0,
+     "unit": "us", "decp": 2, "sep": None, "strip_zeroes": False, "result": "999.00us"},
+    {"value": 1.0,
+     "unit": "ms", "decp": 2, "sep": None, "strip_zeroes": False, "result": "1.00ms"},
+    {"value": 500.0,
+     "unit": "ms", "decp": 2, "sep": " ", "strip_zeroes": False, "result": "500.00 ms"},
+    {"value": 999.0,
+     "unit": "ms", "decp": 2, "sep": " ", "strip_zeroes": False, "result": "999.00 ms"},
+    {"value": 1.0,
+     "unit": "mW", "decp": 2, "sep": " ", "strip_zeroes": False, "result": "1.00 mW"},
+    {"value": 500.0,
+     "unit": "mW", "decp": 1, "sep": " ", "strip_zeroes": True, "result": "500 mW"},
+    {"value": 999.0,
+     "unit": "mW", "decp": 0, "sep": " ", "strip_zeroes": False, "result": "999 mW"},
 ]
 
 def test_num2si():