Fix text loss after zero-width chars, grey 248 quantization, scrollback cap, no-theme sampling, shipped terminal default

- draw(): a zero-width non-combining char (VS16, ZWJ) or a stray control
  byte dropped the rest of the run; skip the char instead
- quantize_256: grey 248 mapped to slot 256 and aborted the SGR
- trim_history: the cap now counts rows above the screen, so a value
  below the screen height (0: no scrollback) no longer cuts the screen
- "No theme" sampled the focused terminal's own colours; sample a
  non-terminal view instead
- vterm.sublime-settings: Apple Terminal is the default again, kitty
  commented out, as the README says

tests/test_commands.py

@@ -25,6 +25,7 @@ class FakeTerminalView:
         self._id = FakeTerminalView._next_id
         FakeTerminalView._next_id += 1
         self._settings = sublime.Settings()
+        self._settings.set("vterm_view", True)
 
     def id(self):
         return self._id
@@ -36,7 +37,24 @@ class FakeTerminalView:
         return True
 
     def style(self):
-        return {}
+        # a terminal view reports its own theme's colours, not the editor's
+        return {"foreground": "#f2f2f2", "background": "#000000"}
+
+
+class FakeEditorView:
+    """An ordinary file view, the one the "No theme" palette is sampled from."""
+
+    def settings(self):
+        return sublime.Settings()
+
+    def is_valid(self):
+        return True
+
+    def style(self):
+        return {"foreground": "#111111", "background": "#eeeeee"}
+
+
+editor = FakeEditorView()
 
 
 class FakeWindow:
@@ -46,6 +64,9 @@ class FakeWindow:
     def active_view(self):
         return self._view
 
+    def views(self):
+        return [self._view, editor]
+
     def show_quick_panel(self, items, on_done, selected_index=-1, on_highlight=None):
         panel.update(items=items, on_done=on_done,
                      selected_index=selected_index, on_highlight=on_highlight)
@@ -105,6 +126,12 @@ command = open_picker(fake_terminal("slate"))
 panel["on_done"](0)
 assert settings.get("theme") is None, settings.get("theme")
 
+# ... and samples the editor's colours, not the themed terminal's own: that
+# would retint every "no theme" terminal with the theme being left
+system = get_scheme_manager(None)
+assert (system.foreground, system.background) == ("#111111", "#eeeeee"), \
+    (system.foreground, system.background)
+
 print("theme picker tests passed ({} themes offered)".format(len(THEMES)))
 
 

tests/test_emulator.py

@@ -119,6 +119,21 @@ def run_case(char_by_char):
     assert screen.buffer[0][0].fg == "ff0000" and screen.buffer[0][0].bold, tag
     assert screen.buffer[0][1].fg == "ff0000", (tag, screen.buffer[0][1].fg)
 
+    # every grey lands inside the palette; 248 used to map to slot 256 and
+    # abort the whole SGR
+    from vterm.emulator import quantize_256
+    assert all(0 <= quantize_256(v, v, v) <= 255 for v in range(256))
+    proc, screen, stream = make()
+    feed(stream, "\x1b[38;2;248;248;248mX", char_by_char)
+    assert screen.buffer[0][0].fg == "ffffff", (tag, screen.buffer[0][0].fg)
+
+    # a zero-width non-combining char (VS16, ZWJ) or a stray control byte is
+    # dropped; the text after it must survive
+    proc, screen, stream = make()
+    feed(stream, "⚠️ warn \U0001F468‍\U0001F4BB ab\x01cd", char_by_char)
+    row = "".join(screen.buffer[0][x].data for x in range(20)).rstrip()
+    assert row == "⚠ warn \U0001F468\U0001F4BB abcd", (tag, repr(row))
+
     # SGR 5/25 (blink): ignored, not a crash — Char has no blink field
     proc, screen, stream = make()
     feed(stream, "\x1b[5;31mX\x1b[25mY", char_by_char)
@@ -315,7 +330,7 @@ GAUNTLET = (
     "\x1b[2;5r\x1b[Sscrolled\x1b[T\x1b[r"
     "\x1b[38:5:100mcolon\x1b[m\r\n"
     "\x1b[2\x073m bel mid-CSI \x1b[3\x18X can cancels\r\n"
-    "wide: 漢字 \x1b[7m漢\x1b[m\r\n"
+    "wide: 漢字 \x1b[7m漢\x1b[m ⚠️ after\r\n"
     "\x1b[m\x1b[;5m\x1b[5;m\x1b[25m params\r\n"
 )
 

tests/test_render.py

@@ -191,17 +191,30 @@ command.trim_history(None, terminal)
 assert terminal.view.text == before, \
     "alt screen view was trimmed: {!r}".format(terminal.view.text)
 
-# the configured cap still applies on the primary screen
+# the configured cap still applies on the primary screen: that many rows of
+# scrollback above the screen
 terminal, stream = make_terminal(rows=5, scrollback=20)
 terminal.offset = 40
 terminal.view = FakeView("\n".join("row {}".format(i) for i in range(40)))
 command = make_command(terminal)
 command.trim_history(None, terminal)
 rows_left = terminal.view.text.count("\n") + 1
-assert rows_left <= 20, rows_left
+assert rows_left <= 25, rows_left
 assert "row 39" in terminal.view.text, "newest rows must survive"
 assert "row 0" not in terminal.view.text, "oldest rows must be dropped"
 
+# a cap below the screen height (0: no scrollback) must never cut the screen
+terminal, stream = make_terminal(rows=10, cols=20, scrollback=0)
+command = make_command(terminal)
+for i in range(3):
+    stream.feed("\r\n".join("row{}".format(i * 10 + j) for j in range(10)) + "\r\n")
+    command.update_lines(None, terminal)
+    command.trim_trailing_spaces(None, terminal)
+    command.trim_history(None, terminal)
+    terminal.screen.dirty.clear()
+assert terminal.offset >= 0, terminal.offset
+assert "row29" in terminal.view.text, terminal.view.text
+
 # below the cap nothing is dropped
 terminal, stream = make_terminal(rows=5, scrollback=5000)
 terminal.offset = 3