Internally, all lines have a trailing "\n".
Buffers created empty (like fifo buffers) start with a single line.
When reading data into fifo buffers, we insert *before* the last line's
trailing newline ("last newline"). This enables autoscrolling (enabled
with "edit -scroll") as long as the cursor is on the last newline.
When autoscrolling is disabled, we have a special case to insert
*after* the last newline. This means that a cursor on that newline
won't be moved. Then we transplant the newline character from the
beginning to the end of the buffer. This special case happens only on
the very first fifo read; on subsequent reads, the cursor at position
1.1 will not be moved anway because insertions happen below 1.1.
Since we always insert (effectively) before the last newline, fifo
buffers have a trailing empty line.
For autoscrolling buffers this seems correct; it gives users an
obvious way to toggle autoscrolling.
For non-scrolling buffers the newline is redundant. Remove it.
This requires keeping track of whether the last newline comes from
the fifo, or was added by us. The shortest fix I could find
is to always append to the buffer if not scrolling, and then delete
the added newline character if applicable.
m_buffer.insert(m_scroll ? pos : m_buffer.next(pos), StringView(data, data+count));
if (not m_scroll and not m_had_trailing_newline)
m_buffer.erase(pos, m_buffer.next(pos));
maybe that's the best fix overall; but erasing at the end seems better
than erasing in the middle, so do that whenever possible.
Reported in https://lists.sr.ht/~mawww/kakoune/%3CZbTK7qit9nzvrMkx@gmail.com%3E
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Regression test
===============
:unified-context-diff: https://en.wikipedia.org/wiki/Diff#Unified_format
Source structure
----------------
----------------------------------------------
.
├── unit
│ └── …
└── compose
└── …
├── [enabled] → applicability
├── [rc] → configuration
├── [in] → start file
├── cmd → command
├── [script] → UI automation
├── [out] → expected end file
├── [kak_*] → expected expansion values
└── [error] → expected error
----------------------------------------------
Usage
-----
To test, just type +run [test]+ in the +test+ directory.
It will print each passing test. If a test fails, a {unified-context-diff}[unified context diff]
is printed showing the test’s expected output and the actual output.
Details
-------
+enabled+ is optional.
If it exists and is executable,
it is invoked with no parameters.
If it exits with a non-zero exit code,
the test is assumed to be not applicable to the current environment
(for example, a test for OS-specific integration
isn't useful on a different OS)
and will be silently skipped.
+rc+ is optional
and should contain a sequence of commands,
_e.g._, +set-option+, +define-command+, +declare-option+.
+rc+ is sourced and evaluated before the +cmd+ key sequence is executed.
+in+ is optional
and should contain the initial text loaded into the input buffer
for editing by the +cmd+ key sequence.
+cmd+ is required
and should contain a key sequence that will edit the input buffer.
+cmd+ is executed after the +rc+ command sequence is sourced.
+script+ is optional
and is a shell-script that will be sourced after +cmd+ is executed.
The special +ui_in+ function sends a string
(expected to be a JSON UI message,
see `doc/json_ui.asciidoc` in the Kakoune source)
to the running Kakoune instance,
while the special +ui_out+ function
checks the next JSON UI messages from Kakoune
against its arguments,
and fails the test if any of them are different.
You can also say `ui_out -ignore N` to ignore the next _N_ JSON UI messages,
where _N_ is a positive integer.
+out+ is optional
and should contain the expected text generated by the +cmd+ key sequence.
If the actual +out+ text
does not match the expected content in the corresponding file,
the unit test will fail.
If there is no +out+
then the unit test will always succeed.
Any +kak_*+ files should match the corresponding expansion
after +cmd+ is complete.
For example, a file named +kak_selection_desc+
should match the +%val{selection_desc}+ expansion.
See `:doc expansions` for a list of available expansions.
If there is an +error+ file,
the test is expected to produce an error.
If Kakoune exits successfully,
or if it fails with the wrong error,
the test is marked as a failure.
582c3c56b2