Image regress tests.

regress/image_test.py

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+"""Helpers for image tests using an attached client on a PTY."""
+
+import contextlib
+import errno
+import fcntl
+import itertools
+import os
+import re
+import select
+import signal
+import struct
+import subprocess
+import sys
+import termios
+import time
+
+
+class Client:
+    """An attached client and the bytes written to its terminal."""
+
+    def __init__(self, pid, fd):
+        self.pid = pid
+        self.fd = fd
+        self.data = bytearray()
+
+    def read(self, duration=0.1):
+        """Read terminal output for a bounded time."""
+        end = time.monotonic() + duration
+        while time.monotonic() < end:
+            if not select.select([self.fd], [], [], 0.01)[0]:
+                continue
+            try:
+                data = os.read(self.fd, 65536)
+            except OSError as e:
+                if e.errno == errno.EIO:
+                    raise RuntimeError("attached client exited") from e
+                raise
+            if not data:
+                raise RuntimeError("attached client exited")
+            self.data.extend(data)
+
+    def clear(self):
+        """Finish reading earlier output before starting a new check."""
+        self.read()
+        self.data.clear()
+
+    def images(self):
+        """Decode complete SIXEL sequences from the terminal output."""
+        return [decode_sixel(body) for body in re.findall(
+            rb"\033P[0-9;]*q(.*?)\033\\", self.data, re.S)]
+
+
+class ImageTest:
+    """A server with one pane which copies input directly to its output."""
+
+    serial = itertools.count()
+
+    def __init__(self, tmux, sx=40, sy=16):
+        # Short, unique socket labels also fit macOS's socket path limit.
+        self.server = [tmux, "-Lis%d-%d" % (os.getpid(), next(self.serial)),
+            "-f/dev/null"]
+        self.sx = sx
+        self.sy = sy
+        self.clients = []
+        self.marker = 0
+
+    def run(self, *args, check=True, input=None):
+        """Run a command on this server."""
+        p = subprocess.run(self.server + list(args), capture_output=True,
+            input=input, timeout=10)
+        if check and p.returncode != 0:
+            raise RuntimeError("%r: %s" % (args, p.stderr.decode()))
+        return p.stdout.decode().strip()
+
+    def wait(self, predicate):
+        """Read client output while waiting for a server state change."""
+        end = time.monotonic() + 10
+        while True:
+            for client in self.clients:
+                client.read(0.01)
+            if predicate():
+                return
+            if time.monotonic() >= end:
+                raise RuntimeError("timed out waiting for server state")
+            time.sleep(0.01)
+
+    def start(self):
+        """Start the pane and skip when the server has no image support."""
+        self.run("new-session", "-d", "-s", "image", "-x", str(self.sx),
+            "-y", str(self.sy), "stty raw -echo; "
+            "printf '\033]2;READY\007'; exec cat")
+        support = self.run("display-message", "-p", "#{image_support}")
+        if support == "0":
+            sys.exit(101)
+        assert support == "1", ("unexpected image_support", support)
+        self.run("set-option", "-g", "status", "off")
+        self.wait(lambda: self.run("display-message", "-p",
+            "#{pane_title}") == "READY")
+
+    def attach(self, graphical=True, utf8=True, cw=8, ch=16, term=None):
+        """Attach a client with a known cell pixel size and image feature."""
+        if term is None:
+            term = "xterm-256color" if graphical else "screen-256color"
+        features = term + (":sixel" if graphical else ":sixel@")
+        self.run("set-option", "-as", "terminal-features", features)
+        pid, fd = os.forkpty()
+        if pid == 0:
+            try:
+                os.environ.pop("TMUX", None)
+                os.environ["TERM"] = term
+                os.environ["LC_ALL"] = "C.UTF-8" if utf8 else "C"
+                fcntl.ioctl(0, termios.TIOCSWINSZ, struct.pack("HHHH",
+                    self.sy, self.sx, self.sx * cw, self.sy * ch))
+                args = self.server + (["-u"] if utf8 else [])
+                os.execv(self.server[0], args +
+                    ["attach-session", "-t", "image"])
+            finally:
+                os._exit(1)
+        client = Client(pid, fd)
+        self.clients.append(client)
+        self.wait(lambda: any(line.startswith(str(pid) + ":") for line in
+            self.run("list-clients", "-F", "#{client_pid}:").splitlines()))
+        # Answer DA so the startup timeout cannot schedule a later redraw.
+        os.write(fd, b"\033[?65;4c" if graphical else b"\033[?65c")
+        self.wait(lambda: self.client_size(client) ==
+            "%dx%d:%dx%d" % (self.sx, self.sy, cw, ch))
+        if len(self.clients) == 1 and cw != 0 and ch != 0:
+            self.wait(lambda: self.run("display-message", "-p",
+                "#{window_cell_width}x#{window_cell_height}") ==
+                "%dx%d" % (cw, ch))
+        client.name = next(line.split(":", 1)[1] for line in
+            self.run("list-clients", "-F",
+                "#{client_pid}:#{client_name}").splitlines()
+            if line.startswith(str(pid) + ":"))
+        client.read(0.2)
+        client.clear()
+        return client
+
+    def client_size(self, client):
+        """Get the character and cell pixel size of one client."""
+        prefix = str(client.pid) + ":"
+        return next((line[len(prefix):] for line in self.run("list-clients",
+            "-F", "#{client_pid}:#{client_width}x#{client_height}:"
+            "#{client_cell_width}x#{client_cell_height}").splitlines()
+            if line.startswith(prefix)), None)
+
+    def send(self, data):
+        """Send literal bytes to the pane."""
+        if len(data) > 512:
+            self.run("load-buffer", "-b", "image", "-", input=data)
+            self.run("paste-buffer", "-b", "image", "-S", "-r", "-d")
+        else:
+            self.run("send-keys", "-H", *["%02x" % ch for ch in data])
+
+    def emit(self, data):
+        """Send pane output and wait until its trailing title is parsed."""
+        for client in self.clients:
+            client.clear()
+        self.marker += 1
+        title = "image-%d" % self.marker
+        self.send(data + b"\033]2;" + title.encode() + b"\007")
+        self.wait(lambda: self.run("display-message", "-p",
+            "#{pane_title}") == title)
+        for client in self.clients:
+            client.read(0.2)
+
+    def redraw(self):
+        """Request a full redraw and collect its terminal output."""
+        for client in self.clients:
+            client.clear()
+        for client in self.clients:
+            self.run("refresh-client", "-t", client.name)
+        for client in self.clients:
+            client.read(0.2)
+
+    def resize(self, client, sx, sy, cw=8, ch=16):
+        """Resize one client's terminal and wait for the window size."""
+        client.clear()
+        fcntl.ioctl(client.fd, termios.TIOCSWINSZ,
+            struct.pack("HHHH", sy, sx, sx * cw, sy * ch))
+        os.kill(client.pid, signal.SIGWINCH)
+        self.wait(lambda: self.client_size(client) ==
+            "%dx%d:%dx%d" % (sx, sy, cw, ch))
+        self.wait(lambda: self.run("display-message", "-p",
+            "#{window_width}x#{window_height}") == "%dx%d" % (sx, sy))
+        client.read(0.2)
+
+    def close(self):
+        """Stop the server and reap every attached client."""
+        self.run("kill-server", check=False)
+        for client in self.clients:
+            os.close(client.fd)
+            if os.waitpid(client.pid, os.WNOHANG) == (0, 0):
+                os.kill(client.pid, signal.SIGTERM)
+                os.waitpid(client.pid, 0)
+
+
+@contextlib.contextmanager
+def image_test(tmux, sx=40, sy=16):
+    """Clean up the server even when a test fails or skips."""
+    test = ImageTest(tmux, sx, sy)
+    try:
+        test.start()
+        yield test
+    finally:
+        test.close()
+
+
+def sixel(w, h, palette, pixels, p2=1):
+    """Build SIXEL input from a palette and row-major palette indexes."""
+    assert len(pixels) == w * h
+    out = ['\033P9;%dq"1;1;%d;%d' % (p2, w, h)]
+    for c, rgb in enumerate(palette):
+        out.append("#%d;2;%d;%d;%d" % (c, *rgb))
+    for y in range(0, h, 6):
+        planes = []
+        for c in range(len(palette)):
+            columns = []
+            for x in range(w):
+                bits = sum(1 << bit for bit in range(min(6, h - y))
+                    if pixels[(y + bit) * w + x] == c)
+                columns.append(chr(0x3f + bits))
+            if all(ch == "?" for ch in columns):
+                continue
+            plane = "#%d" % c
+            for ch, run in itertools.groupby(columns):
+                n = len(list(run))
+                plane += "!%d%s" % (n, ch) if n > 3 else ch * n
+            planes.append(plane)
+        out.append("$".join(planes))
+        if y + 6 < h:
+            out.append("-")
+    out.append("\033\\")
+    return "".join(out).encode()
+
+
+def decode_sixel(body):
+    """Read RGB output pixels without using tmux's SIXEL decoder."""
+    attributes = re.match(rb'"1;1;(\d+);(\d+)', body)
+    assert attributes is not None, ("missing raster attributes", body[:80])
+    w, h = map(int, attributes.groups())
+    pixels = [None] * (w * h)
+    palette = {}
+    c = x = y = 0
+    pos = attributes.end()
+    while pos < len(body):
+        ch = body[pos]
+        pos += 1
+        if ch == ord("#"):
+            match = re.match(rb"(\d+)(?:;2;(\d+);(\d+);(\d+))?", body[pos:])
+            assert match is not None, body[pos:pos + 80]
+            c = int(match[1])
+            if match[2] is not None:
+                rgb = tuple(int(match[i]) for i in range(2, 5))
+                assert all(v <= 100 for v in rgb), rgb
+                palette[c] = tuple((v * 255 + 50) // 100 for v in rgb)
+            pos += match.end()
+            continue
+        if ch == ord("$"):
+            x = 0
+            continue
+        if ch == ord("-"):
+            x = 0
+            y += 6
+            continue
+        n = 1
+        if ch == ord("!"):
+            match = re.match(rb"(\d+)(.)", body[pos:], re.S)
+            assert match is not None
+            n = int(match[1])
+            ch = match[2][0]
+            pos += match.end()
+        assert 0x3f <= ch <= 0x7e, ch
+        for bit in range(6):
+            if not (ch - 0x3f) & (1 << bit):
+                continue
+            assert y + bit < h and x + n <= w, (x, y, n, bit, w, h)
+            assert c in palette, ("undefined output colour", c)
+            for xx in range(x, x + n):
+                pixels[(y + bit) * w + xx] = palette[c]
+        x += n
+    return w, h, pixels
+
+
+def check_image(image, w, h, expected):
+    """Compare decoded output with expected RGB pixels and transparency."""
+    assert image[:2] == (w, h), (image[:2], (w, h))
+    assert len(expected) == w * h
+    for i, (actual, wanted) in enumerate(zip(image[2], expected)):
+        if wanted is None:
+            assert actual is None, (i % w, i // w, actual, wanted)
+        else:
+            assert actual is not None, (i % w, i // w, actual, wanted)
+            assert max(abs(a - b) for a, b in zip(actual, wanted)) <= 3, (
+                i % w, i // w, actual, wanted)