gdb/testsuite: add tests for Term

While trying to review Andrew's patch here [1], I thought I spotted a
bug in the handling of a CSI, but I had no way to know for sure.  So I
thought it would be useful to have unit tests for the handling of
control characters and control sequences of our toy terminal
implementation.  It might help avoid chasing bugs in the GDB TUI when in
reality it's a problem with the testsuite's terminal implementation.

Add the gdb.tui/tuiterm.exp file to do that.  All currently supported
control sequences and characters are tested, except _csi_m (the one that
handles colors and stuff).  _csi_m should probably be tested too, but it
will require more work.

Fix a few issues that the tests spotted:

 - backspace: according to [3] (table 4-1), a backspace when the cursor
   is at the beginning of a line should have no effect.  Our
   implementation did wrap to the end of the previous line.  Change our
   implementation to match the doc (and the test).
 - insert character: this control sequence is supposed to insert blank
   characters, shifting all the rest of the line right.  The current
   implementation moves N characters right, but it overwrites the
   characters on the right instead of shifting them.  It also doesn't
   insert blank characters at the cursor.
 - Cursor down, forward, next line: off-by-one error when reaching the
   end of the display.
 - erase in display, line: off-by-one errors.
 - vertical line position absolute: allowed setting the cursor outside
   the display, when it should clamp it to the display size.

I found that this web page [2] gave some good clues on the expected
behavior of some control characters or sequences that some other pages
didn't.

[1] https://sourceware.org/pipermail/gdb-patches/2022-March/186433.html
[2] https://docs.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences
[3] https://vt100.net/docs/vt510-rm/chapter4.html#S4.3.3

Change-Id: Iab4141fdcfb7459d1b7c45cc63bd1fcb50a78d5d

1 files changed, 615 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.tui/tuiterm.exp b/gdb/testsuite/gdb.tui/tuiterm.exp
new file mode 100644
index 0000000..6b1b044
--- /dev/null
+++ b/gdb/testsuite/gdb.tui/tuiterm.exp
@@ -0,0 +1,615 @@
+# Copyright 2022 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Unit-test Term, the testsuite's terminal implementation that is used to test
+# the TUI.
+
+tuiterm_env
+
+# Validate the cursor position.
+#
+# EXPECTED_CUR_COL and EXPECTED_CUR_ROW are the expected cursor column and row
+# positions.
+
+proc check_cursor_position { test expected_cur_col expected_cur_row } {
+    with_test_prefix $test {
+	gdb_assert {$expected_cur_col == ${Term::_cur_col}} "column"
+	gdb_assert {$expected_cur_row == ${Term::_cur_row}} "row"
+    }
+}
+
+# Validate the terminal contents and cursor position.
+#
+# EXPECTED_CONTENTS must be a list of strings, one element for each terminal
+# line.
+#
+# EXPECTED_CUR_COL and EXPECTED_CUR_ROW are passed to check_cursor_position.
+
+proc check { test expected_contents expected_cur_col expected_cur_row } {
+    with_test_prefix $test {
+	# Check term contents.
+	set regexp "^"
+
+	foreach line $expected_contents {
+	    append regexp $line
+	    append regexp "\n"
+	}
+
+	append regexp "$"
+	Term::check_contents "contents" $regexp
+    }
+
+    check_cursor_position $test $expected_cur_col $expected_cur_row
+}
+
+proc setup_terminal { cols rows } {
+    setenv TERM ansi
+    Term::_setup $rows $cols
+}
+
+# Most tests are fine with a small terminal.  This proc initializes the terminal
+# with 8 columns and 4 rows, with the following content:
+#
+#   abcdefgh
+#   ijklmnop
+#   qrstuvwx
+#   yz01234
+#
+# The bottom right cell is left blank: trying to write to it using _insert
+# would move the cursor past the screen, causing a scroll, but scrolling is
+# not implemented at the moment.
+
+proc setup_small {} {
+    setup_terminal 8 4
+
+    Term::_insert "abcdefgh"
+    Term::_insert "ijklmnop"
+    Term::_insert "qrstuvwx"
+    Term::_insert "yz01234"
+
+    check "check after setup" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 7 3
+}
+
+# Some tests require a larger terminal.  This proc initializes the terminal with
+# 80 columns and 25 rows, but leaves the content empty.
+
+proc setup_large {} {
+    setup_terminal 80 25
+}
+
+# Each proc below tests a control character or sequence individually.
+
+proc test_backspace {} {
+    # Note: the backspace (BS) control character only moves the cursor left,
+    # it does not delete characters.
+
+    Term::_move_cursor 1 2
+
+    Term::_ctl_0x08
+    check "backspace one" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 2
+
+    # Cursor should not move if it is already at column 0.
+    Term::_ctl_0x08
+    check "backspace 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 2
+}
+
+proc test_linefeed { } {
+    Term::_move_cursor 1 2
+    Term::_ctl_0x0a
+    check "linefeed" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 1 3
+}
+
+proc test_carriage_return { } {
+    Term::_move_cursor 1 2
+    Term::_ctl_0x0d
+    check "carriage return 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 2
+
+    Term::_ctl_0x0d
+    check "carriage return 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 2
+}
+
+proc test_insert_characters { } {
+    Term::_move_cursor 1 2
+
+    Term::_csi_@
+    check "insert characters 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"q rstuvw"
+	"yz01234 "
+    } 1 2
+
+    Term::_csi_@ 20
+    check "insert characters 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"q       "
+	"yz01234 "
+    } 1 2
+
+    Term::_move_cursor 0 1
+    Term::_csi_@ 6
+    check "insert characters 3" {
+	"abcdefgh"
+	"      ij"
+	"q       "
+	"yz01234 "
+    } 0 1
+}
+
+proc test_cursor_up { } {
+    Term::_move_cursor 2 3
+
+    Term::_csi_A
+    check "cursor up 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 2 2
+
+    Term::_csi_A 2
+    check "cursor up 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 2 0
+
+    Term::_csi_A 1
+    check "cursor up 3" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 2 0
+}
+
+proc test_cursor_down { } {
+    Term::_move_cursor 1 0
+
+    Term::_csi_B
+    check "cursor down 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 1 1
+
+    Term::_csi_B 2
+    check "cursor down 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 1 3
+
+    Term::_csi_B 1
+    check "cursor down 3" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 1 3
+}
+
+proc test_cursor_forward { } {
+    Term::_move_cursor 0 1
+
+    Term::_csi_C
+    check "cursor forward 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 1 1
+
+    Term::_csi_C 6
+    check "cursor forward 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 7 1
+
+    Term::_csi_C 1
+    check "cursor forward 3" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 7 1
+}
+
+proc test_cursor_backward { } {
+    Term::_move_cursor 7 1
+
+    Term::_csi_D
+    check "cursor backward 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 6 1
+
+    Term::_csi_D 6
+    check "cursor backward 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 1
+
+    Term::_csi_D 1
+    check "cursor backward 3" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 1
+}
+
+proc test_cursor_next_line { } {
+    Term::_move_cursor 2 0
+
+    Term::_csi_E
+    check "cursor next line 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 1
+
+    Term::_move_cursor 2 1
+    Term::_csi_E 2
+    check "cursor next line 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 3
+
+    Term::_move_cursor 2 3
+    Term::_csi_E 1
+    check "cursor next line 3" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 3
+}
+
+proc test_cursor_previous_line { } {
+    Term::_move_cursor 2 3
+
+    Term::_csi_F
+    check "cursor previous line 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 2
+
+    Term::_move_cursor 2 2
+    Term::_csi_F 2
+    check "cursor previous line 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 0
+
+    Term::_move_cursor 2 0
+    Term::_csi_F 1
+    check "cursor previous line 3" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 0
+}
+
+proc test_horizontal_absolute { } {
+    Term::_move_cursor 2 2
+    Term::_csi_G
+    check "cursor horizontal absolute 1" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 0 2
+
+    Term::_move_cursor 2 2
+    Term::_csi_G 4
+    check "cursor horizontal absolute 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 3 2
+}
+
+proc test_cursor_position { } {
+    Term::_move_cursor 1 1
+
+    Term::_csi_H 3 5
+    check "cursor horizontal absolute 2" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 4 2
+}
+
+proc test_cursor_horizontal_forward_tabulation { } {
+    Term::_move_cursor 5 2
+    Term::_csi_I
+    check_cursor_position "default param" 8 2
+
+    Term::_csi_I 2
+    check_cursor_position "explicit param" 24 2
+
+    Term::_move_cursor 77 2
+    Term::_csi_I 5
+    check_cursor_position "try to go past the end" 79 2
+}
+
+proc test_erase_in_display { } {
+    Term::_move_cursor 5 2
+    Term::_csi_J
+    check "erase in display, cursor to end with default param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstu   "
+	"        "
+    } 5 2
+
+    Term::_move_cursor 3 2
+    Term::_csi_J 0
+    check "erase in display, cursor to end with explicit param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrs     "
+	"        "
+    } 3 2
+
+    Term::_move_cursor 2 1
+    Term::_csi_J 1
+    check "erase in display, beginning to cursor" {
+	"        "
+	"   lmnop"
+	"qrs     "
+	"        "
+    } 2 1
+
+    Term::_move_cursor 5 1
+    Term::_csi_J 2
+    check "erase in display, entire display" {
+	"        "
+	"        "
+	"        "
+	"        "
+    } 5 1
+}
+
+proc test_erase_in_line { } {
+    Term::_move_cursor 5 2
+    Term::_csi_K
+    check "erase in line, cursor to end with default param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstu   "
+	"yz01234 "
+    } 5 2
+
+    Term::_move_cursor 3 2
+    Term::_csi_K 0
+    check "erase in line, cursor to end with explicit param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrs     "
+	"yz01234 "
+    } 3 2
+
+    Term::_move_cursor 3 1
+    Term::_csi_K 1
+    check "erase in line, beginning to cursor" {
+	"abcdefgh"
+	"    mnop"
+	"qrs     "
+	"yz01234 "
+    } 3 1
+
+    Term::_move_cursor 3 0
+    Term::_csi_K 2
+    check "erase in line, entire line" {
+	"        "
+	"    mnop"
+	"qrs     "
+	"yz01234 "
+    } 3 0
+}
+
+proc test_delete_line { } {
+    Term::_move_cursor 3 2
+    Term::_csi_M
+    check "delete line, default param" {
+	"abcdefgh"
+	"ijklmnop"
+	"yz01234 "
+	"        "
+    } 3 2
+
+    Term::_move_cursor 3 0
+    Term::_csi_M 2
+    check "delete line, explicit param" {
+	"yz01234 "
+	"        "
+	"        "
+	"        "
+    } 3 0
+}
+
+proc test_erase_character { } {
+    Term::_move_cursor 3 2
+    Term::_csi_X
+    check "erase character, default param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrs uvwx"
+	"yz01234 "
+    } 3 2
+
+    Term::_move_cursor 1 3
+    Term::_csi_X 4
+    check "erase character, explicit param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrs uvwx"
+	"y    34 "
+    } 1 3
+}
+
+proc test_cursor_backward_tabulation { } {
+    Term::_move_cursor 77 2
+    Term::_csi_Z
+    check_cursor_position "default param" 72 2
+
+    Term::_csi_Z 2
+    check_cursor_position "explicit param" 56 2
+
+    Term::_move_cursor 6 2
+    Term::_csi_Z 12
+    check_cursor_position "try to go past the beginning" 0 2
+}
+
+proc test_repeat { } {
+    Term::_move_cursor 2 1
+    set Term::_last_char X
+
+    Term::_csi_b 3
+    check "repeat" {
+	"abcdefgh"
+	"ijXXXnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 5 1
+}
+
+proc test_vertical_line_position_absolute { } {
+    Term::_move_cursor 2 1
+
+    Term::_csi_d
+    check "default param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 2 0
+
+    Term::_csi_d 3
+    check "explicit param" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 2 2
+
+    Term::_csi_d 100
+    check "try to move off-display" {
+	"abcdefgh"
+	"ijklmnop"
+	"qrstuvwx"
+	"yz01234 "
+    } 2 3
+}
+
+# Run proc TEST_PROC_NAME with a "small" terminal.
+
+proc run_one_test_small { test_proc_name } {
+    save_vars { env(TERM) stty_init } {
+	setup_small
+	eval $test_proc_name
+    }
+}
+
+# Run proc TEST_PROC_NAME with a "large" terminal.
+
+proc run_one_test_large { test_proc_name } {
+    save_vars { env(TERM) stty_init } {
+	setup_large
+	eval $test_proc_name
+    }
+}
+
+foreach_with_prefix test {
+    test_backspace
+    test_linefeed
+    test_carriage_return
+    test_insert_characters
+    test_cursor_up
+    test_cursor_down
+    test_cursor_forward
+    test_cursor_backward
+    test_cursor_next_line
+    test_cursor_previous_line
+    test_horizontal_absolute
+    test_cursor_position
+    test_erase_in_display
+    test_erase_in_line
+    test_delete_line
+    test_erase_character
+    test_repeat
+    test_vertical_line_position_absolute
+} {
+    run_one_test_small $test
+}
+
+foreach_with_prefix test {
+    test_cursor_horizontal_forward_tabulation
+    test_cursor_backward_tabulation
+} {
+    run_one_test_large $test
+}