Consolidate duration formatting functions in report.py (#243)

src/copilot_usage/report.py

@@ -61,6 +61,21 @@ def format_tokens(n: int) -> str:
     return str(n)
 
 
+def _format_timedelta(td: timedelta) -> str:
+    """Format a timedelta to human-readable duration (e.g. '1h 5m 30s')."""
+    total_seconds = max(int(td.total_seconds()), 0)
+    hours, remainder = divmod(total_seconds, 3600)
+    minutes, seconds = divmod(remainder, 60)
+    parts: list[str] = []
+    if hours:
+        parts.append(f"{hours}h")
+    if minutes:
+        parts.append(f"{minutes}m")
+    if seconds or not parts:
+        parts.append(f"{seconds}s")
+    return " ".join(parts)
+
+
 def format_duration(ms: int) -> str:
     """Format milliseconds to human-readable duration.
 
@@ -74,36 +89,16 @@ def format_duration(ms: int) -> str:
         >>> format_duration(3661000)
         '1h 1m 1s'
     """
-    if ms <= 0:
-        return "0s"
-    total_seconds = ms // 1000
-    hours = total_seconds // 3600
-    minutes = (total_seconds % 3600) // 60
-    seconds = total_seconds % 60
-
-    parts: list[str] = []
-    if hours:
-        parts.append(f"{hours}h")
-    if minutes:
-        parts.append(f"{minutes}m")
-    if seconds or not parts:
-        parts.append(f"{seconds}s")
-    return " ".join(parts)
+    return _format_timedelta(timedelta(milliseconds=ms))
 
 
 def _format_elapsed_since(start: datetime) -> str:
     """Return a human-readable elapsed time from *start* to now.
 
-    Formats as ``Xh Ym`` when >= 1 hour, otherwise ``Ym Zs``.
+    Formats using :func:`_format_timedelta` for consistent output.
     """
-    now = datetime.now(tz=UTC)
-    delta = now - ensure_aware(start)
-    total_seconds = max(int(delta.total_seconds()), 0)
-    hours, remainder = divmod(total_seconds, 3600)
-    minutes, seconds = divmod(remainder, 60)
-    if hours > 0:
-        return f"{hours}h {minutes}m"
-    return f"{minutes}m {seconds}s"
+    delta = datetime.now(tz=UTC) - ensure_aware(start)
+    return _format_timedelta(delta)
 
 
 def _estimated_output_tokens(session: SessionSummary) -> int:
@@ -295,15 +290,7 @@ def _format_detail_duration(
     """Return a human-readable duration string between two timestamps."""
     if start is None or end is None:
         return "—"
-    delta = end - start
-    total_seconds = max(int(delta.total_seconds()), 0)
-    if total_seconds < 60:
-        return f"{total_seconds}s"
-    minutes, seconds = divmod(total_seconds, 60)
-    if minutes < 60:
-        return f"{minutes}m {seconds}s"
-    hours, minutes = divmod(minutes, 60)
-    return f"{hours}h {minutes}m"
+    return _format_timedelta(end - start)
 
 
 def _event_type_label(event_type: str) -> Text:

tests/copilot_usage/test_report.py

@@ -33,6 +33,7 @@
     _format_elapsed_since,
     _format_relative_time,
     _format_session_running_time,
+    _format_timedelta,
     _has_active_period_stats,
     _render_model_table,
     _render_shutdown_cycles,
@@ -2895,12 +2896,12 @@ def test_minutes_seconds_branch(self) -> None:
         assert result == "5m 30s"
 
     def test_zero_elapsed(self) -> None:
-        """When start == now, format is '0m 0s'."""
+        """When start == now, format is '0s'."""
         now = datetime(2025, 6, 1, 12, 0, 0, tzinfo=UTC)
         with patch("copilot_usage.report.datetime", wraps=datetime) as mock_dt:
             mock_dt.now.return_value = now
             result = _format_elapsed_since(now)
-        assert result == "0m 0s"
+        assert result == "0s"
 
 
 # ---------------------------------------------------------------------------
@@ -2910,16 +2911,14 @@ def test_zero_elapsed(self) -> None:
 
 class TestFormatDetailDurationBoundaries:
     def test_exactly_60_seconds(self) -> None:
-        """60s sits on the < 60 boundary — should produce '1m 0s'."""
+        """60s sits on the < 60 boundary — should produce '1m'."""
         start = datetime(2025, 1, 1, tzinfo=UTC)
-        assert _format_detail_duration(start, start + timedelta(seconds=60)) == "1m 0s"
+        assert _format_detail_duration(start, start + timedelta(seconds=60)) == "1m"
 
     def test_exactly_3600_seconds(self) -> None:
-        """3600s sits on the minutes < 60 boundary — should produce '1h 0m'."""
+        """3600s sits on the minutes < 60 boundary — should produce '1h'."""
         start = datetime(2025, 1, 1, tzinfo=UTC)
-        assert (
-            _format_detail_duration(start, start + timedelta(seconds=3600)) == "1h 0m"
-        )
+        assert _format_detail_duration(start, start + timedelta(seconds=3600)) == "1h"
 
     def test_start_none(self) -> None:
         """None start should return em-dash."""
@@ -2930,3 +2929,40 @@ def test_end_none(self) -> None:
         """None end should return em-dash."""
         start = datetime(2025, 1, 1, tzinfo=UTC)
         assert _format_detail_duration(start, None) == "—"
+
+
+# ---------------------------------------------------------------------------
+# Issue #243 — Unit tests for _format_timedelta core helper
+# ---------------------------------------------------------------------------
+
+
+class TestFormatTimedelta:
+    def test_zero(self) -> None:
+        assert _format_timedelta(timedelta(0)) == "0s"
+
+    def test_seconds_only(self) -> None:
+        assert _format_timedelta(timedelta(seconds=5)) == "5s"
+
+    def test_minutes_and_seconds(self) -> None:
+        assert _format_timedelta(timedelta(minutes=6, seconds=29)) == "6m 29s"
+
+    def test_exact_minute(self) -> None:
+        assert _format_timedelta(timedelta(minutes=1)) == "1m"
+
+    def test_exact_hour(self) -> None:
+        assert _format_timedelta(timedelta(hours=1)) == "1h"
+
+    def test_hours_minutes_seconds(self) -> None:
+        assert _format_timedelta(timedelta(hours=1, minutes=1, seconds=1)) == "1h 1m 1s"
+
+    def test_hours_and_minutes_no_seconds(self) -> None:
+        assert _format_timedelta(timedelta(hours=2, minutes=30)) == "2h 30m"
+
+    def test_negative_clamped_to_zero(self) -> None:
+        assert _format_timedelta(timedelta(seconds=-10)) == "0s"
+
+    def test_large_duration(self) -> None:
+        assert (
+            _format_timedelta(timedelta(hours=100, minutes=5, seconds=3))
+            == "100h 5m 3s"
+        )