add unit tests for util.human_size

2 files changed, 22 insertions, 2 deletions

diff --git a/fietsboek/util.py b/fietsboek/util.py
index ecd2f31..acbb45d 100644
--- a/fietsboek/util.py
+++ b/fietsboek/util.py
@@ -210,12 +210,16 @@ def human_size(num_bytes: int) -> str:
     """
     num_bytes = float(num_bytes)
     suffixes = ["B", "KiB", "MiB", "GiB"]
+    prefix = ""
+    if num_bytes < 0:
+        prefix = "-"
+        num_bytes = -num_bytes
     for suffix in suffixes:
         if num_bytes < 1024 or suffix == suffixes[-1]:
             if suffix == "B":
                 # Don't do the decimal point for bytes
-                return f"{int(num_bytes)} {suffix}"
-            return f"{num_bytes:.1f} {suffix}"
+                return f"{prefix}{int(num_bytes)} {suffix}"
+            return f"{prefix}{num_bytes:.1f} {suffix}"
         num_bytes /= 1024
     # Unreachable:
     return ""
diff --git a/tests/unit/test_util.py b/tests/unit/test_util.py
index 1a56911..6dc8e7d 100644
--- a/tests/unit/test_util.py
+++ b/tests/unit/test_util.py
@@ -88,6 +88,22 @@ def test_tour_metadata(gpx_file):
 def test_mps_to_kph(mps, kph):
     assert util.mps_to_kph(mps) == pytest.approx(kph, 0.1)
 
+@pytest.mark.parametrize('num_bytes, expected', [
+    (1, '1 B'),
+    (1023, '1023 B'),
+    (1024, '1.0 KiB'),
+    (1536, '1.5 KiB'),
+    (1024 ** 2, '1.0 MiB'),
+    (1024 ** 3, '1.0 GiB'),
+    (0, '0 B'),
+    # Negative sizes in itself are a bit weird, but they make sense as the
+    # difference between two size values, so they should still work.
+    (-1, '-1 B'),
+    (-1024, '-1.0 KiB'),
+])
+def test_human_size(num_bytes, expected):
+    assert util.human_size(num_bytes) == expected
+
 
 def test_tile_url(app_request):
     route_url = util.tile_url(app_request, "tile-proxy", provider="bobby")