init

tests/test_reports.py

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+from datetime import date
+
+from common_cents.screens.reports import (
+    _date_range,
+    _month_options,
+    _months_in_range,
+)
+
+
+def test_months_in_range_same_month():
+    assert _months_in_range("2026-05-01", "2026-05-31") == 1
+
+
+def test_months_in_range_multi_month():
+    assert _months_in_range("2026-01-01", "2026-12-31") == 12
+
+
+def test_months_in_range_year_crossover():
+    assert _months_in_range("2025-11-01", "2026-02-15") == 4
+
+
+def test_date_range_this_month():
+    import calendar
+
+    start, end, label = _date_range("this-month")
+    today = date.today()
+    last_day = calendar.monthrange(today.year, today.month)[1]
+    assert start == today.replace(day=1).isoformat()
+    assert end == today.replace(day=last_day).isoformat()
+    assert "This Month" in label
+
+
+def test_date_range_last_month():
+    start, end, _label = _date_range("last-month")
+    today = date.today()
+    end_d = date.fromisoformat(end)
+    # last day of previous month
+    assert end_d < today.replace(day=1)
+    assert date.fromisoformat(start).day == 1
+    assert end_d.month == date.fromisoformat(start).month
+
+
+def test_date_range_ytd():
+    start, end, _label = _date_range("ytd")
+    today = date.today()
+    assert start == date(today.year, 1, 1).isoformat()
+    assert end == today.isoformat()
+
+
+def test_date_range_last_12_months():
+    """Trailing 12 months = current month + 11 prior, so spans 12 distinct months."""
+    start, end, _label = _date_range("last-12")
+    assert _months_in_range(start, end) == 12
+
+
+def test_date_range_custom_month_bounds():
+    """Custom range expands YYYY-MM to first/last day of the chosen months."""
+    start, end, label = _date_range("custom", "2026-03", "2026-05")
+    assert start == "2026-03-01"
+    assert end == "2026-05-31"
+    assert "Mar 2026" in label and "May 2026" in label
+
+
+def test_date_range_custom_single_month():
+    start, end, label = _date_range("custom", "2026-02", "2026-02")
+    assert start == "2026-02-01"
+    assert end == "2026-02-28"
+    assert label == "Custom (Feb 2026)"
+
+
+def test_date_range_custom_swaps_when_inverted():
+    start, end, _label = _date_range("custom", "2026-12", "2026-01")
+    assert start == "2026-01-01"
+    assert end == "2026-12-31"
+
+
+def test_date_range_custom_falls_back_to_current_month_when_blank():
+    start, end, _label = _date_range("custom", "", "")
+    today = date.today()
+    assert start.startswith(today.strftime("%Y-%m"))
+    assert start.endswith("-01")
+    assert end.startswith(today.strftime("%Y-%m"))
+
+
+def test_month_options_descending_and_inclusive():
+    opts = _month_options(date(2026, 3, 1), date(2026, 5, 15))
+    # latest first, three months, label = abbr month + year, value = YYYY-MM
+    assert opts == [
+        ("May 2026", "2026-05"),
+        ("Apr 2026", "2026-04"),
+        ("Mar 2026", "2026-03"),
+    ]
+
+
+def test_month_options_year_crossover():
+    opts = _month_options(date(2025, 11, 1), date(2026, 1, 31))
+    assert [v for _, v in opts] == ["2026-01", "2025-12", "2025-11"]