sidebar: a talkative pane can no longer cost you a tab

Rows were spent in tab order until they ran out, so statuses from early tabs
simply consumed the rows later tabs needed for their labels. Four tabs of
three announcing panes in a sixteen-row terminal left the fourth tab with no
row and no hit anywhere on the sidebar -- not clipped, unreachable -- and the
new-tab button went with it.

The list is the navigation and a status is an annotation on it, so the
annotation is what gives way. Before drawing a tab's statuses, reserve a row
for each tab still to come and one for the button, and allow the statuses
only what is left over. The "and more" ellipsis is measured against that
allowance rather than the cap, so a list cut short by the height still says
it was cut, the same as one cut short by the setting.

The pad is deliberately not reserved: it already gives itself up a cell at a
time, which is the same order of surrender -- spacing, then extra statuses,
then statuses, never the thing they are about.

1 files changed, 45 insertions, 0 deletions

diff --git a/tests/test_tab_bar.py b/tests/test_tab_bar.py
index 1fb6609..925b068 100644
--- a/tests/test_tab_bar.py
+++ b/tests/test_tab_bar.py
@@ -305,6 +305,50 @@ def test_status_cap_spends_its_last_row_on_the_ellipsis():
         )
 
 
+def test_statuses_never_cost_a_tab_its_row():
+    """The list is the navigation; a status is an annotation on it.
+
+    Rows used to be spent in tab order until they ran out, so talkative panes
+    early in the list simply consumed the rows later tabs needed: four tabs of
+    three announcing panes in a short terminal left the fourth with no row and
+    no hit at all -- not clipped, unreachable -- and took the new-tab button
+    with it. What gives way now is the annotation."""
+    cfg = _cfg(f'tab_bar_side "left"\ntab_bar_width {W}\ntab_bar_status 3\n')
+    with Session(SH, cols=90, rows=16, config=cfg) as s:
+        s.settle(30)
+        for t in range(4):
+            if t:
+                s.api("new-tab")
+                s.settle(20)
+            _status(s, f"tab{t + 1} pane1")
+            for p in (2, 3):
+                s.api("split", dir="rows")
+                s.settle(20)
+                _status(s, f"tab{t + 1} pane{p}")
+
+        snap = s.snapshot()
+        targets = {h["action"] for h in snap.hits}
+        missing = [t["index"] for t in s.tabs() if f"tab:{t['index']}" not in targets]
+        check("every tab that exists can be clicked", not missing, str(missing))
+        check("the button was not crowded out either", "newtab" in targets, str(sorted(targets)))
+        # The annotation is what gave way: with four labels and a button to
+        # fit into sixteen rows there is no room for twelve statuses, and it
+        # is the last tabs' statuses that are missing rather than their rows.
+        # The sidebar's own columns only: the panes' frames carry these same
+        # words (a pane draws its status too), and would match anywhere.
+        bar = [_row(snap, y) for y in range(16)]
+        check(
+            "the statuses are what went",
+            not any("tab4" in r for r in bar),
+            repr([r for r in bar if r.strip()]),
+        )
+        check(
+            "...and the ones that fit are still there",
+            any("tab1 pane1" in r for r in bar),
+            repr([r for r in bar if r.strip()]),
+        )
+
+
 def test_a_long_status_is_cut_and_says_so():
     with Session(SH, cols=90, rows=20, config=LEFT) as s:
         s.settle(30)
@@ -575,6 +619,7 @@ if __name__ == "__main__":
     test_the_sidebar_button_says_what_it_does()
     test_newtab_pad_is_the_air_before_the_button()
     test_newtab_button_false_removes_it_everywhere()
+    test_statuses_never_cost_a_tab_its_row()
     test_a_narrow_sidebar_keeps_the_bare_mark()
     test_the_strip_keeps_its_bare_mark()
     test_narrow_terminal_falls_back_to_top()