tests: Add htmldocck.py script for the use of Rustdoc tests.

The script is intended as a tool for doing every sort of verifications
amenable to Rustdoc's HTML output. For example, link checkers would go
to this script. It already parses HTML into a document tree form (with
a slight caveat), so future tests can make use of it.

As an example, relevant `rustdoc-*` run-make tests have been updated
to use `htmldocck.py` and got their `verify.sh` removed. In the future
they may go to a dedicated directory with htmldocck running by default.
The detailed explanation of test scripts is provided as a docstring of
htmldocck.

cc #19723

1 files changed, 316 insertions, 0 deletions

diff --git a/src/etc/htmldocck.py b/src/etc/htmldocck.py
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+# Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution and at
+# http://rust-lang.org/COPYRIGHT.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+r"""
+htmldocck.py is a custom checker script for Rustdoc HTML outputs.
+
+# How and why?
+
+The principle is simple: This script receives a path to generated HTML
+documentation and a "template" script, which has a series of check
+commands like `@has` or `@matches`. Each command can be used to check if
+some pattern is present or not present in the particular file or in
+the particular node of HTML tree. In many cases, the template script
+happens to be a source code given to rustdoc.
+
+While it indeed is possible to test in smaller portions, it has been
+hard to construct tests in this fashion and major rendering errors were
+discovered much later. This script is designed for making the black-box
+and regression testing of Rustdoc easy. This does not preclude the needs
+for unit testing, but can be used to complement related tests by quickly
+showing the expected renderings.
+
+In order to avoid one-off dependencies for this task, this script uses
+a reasonably working HTML parser and the existing XPath implementation
+from Python 2's standard library. Hopefully we won't render
+non-well-formed HTML.
+
+# Commands
+
+Commands start with an `@` followed by a command name (letters and
+hyphens), and zero or more arguments separated by one or more whitespace
+and optionally delimited with single or double quotes. The `@` mark
+cannot be preceded by a non-whitespace character. Other lines (including
+every text up to the first `@`) are ignored, but it is recommended to
+avoid the use of `@` in the template file.
+
+There are a number of supported commands:
+
+* `@has PATH` checks for the existence of given file.
+
+  `PATH` is relative to the output directory. It can be given as `-`
+  which repeats the most recently used `PATH`.
+
+* `@has PATH PATTERN` and `@matches PATH PATTERN` checks for
+  the occurrence of given `PATTERN` in the given file. Only one
+  occurrence of given pattern is enough.
+
+  For `@has`, `PATTERN` is a whitespace-normalized (every consecutive
+  whitespace being replaced by one single space character) string.
+  The entire file is also whitespace-normalized including newlines.
+
+  For `@matches`, `PATTERN` is a Python-supported regular expression.
+  The file remains intact but the regexp is matched with no `MULTILINE`
+  and `IGNORECASE` option. You can still use a prefix `(?m)` or `(?i)`
+  to override them, and `\A` and `\Z` for definitely matching
+  the beginning and end of the file.
+
+  (The same distinction goes to other variants of these commands.)
+
+* `@has PATH XPATH PATTERN` and `@matches PATH XPATH PATTERN` checks for
+  the presence of given `XPATH` in the given HTML file, and also
+  the occurrence of given `PATTERN` in the matching node or attribute.
+  Only one occurrence of given pattern in the match is enough.
+
+  `PATH` should be a valid and well-formed HTML file. It does *not*
+  accept arbitrary HTML5; it should have matching open and close tags
+  and correct entity references at least.
+
+  `XPATH` is an XPath expression to match. This is fairly limited:
+  `tag`, `*`, `.`, `//`, `..`, `[@attr]`, `[@attr='value']`, `[tag]`,
+  `[POS]` (element located in given `POS`), `[last()-POS]`, `text()`
+  and `@attr` (both as the last segment) are supported. Some examples:
+
+  - `//pre` or `.//pre` matches any element with a name `pre`.
+  - `//a[@href]` matches any element with an `href` attribute.
+  - `//*[@class="impl"]//code` matches any element with a name `code`,
+    which is an ancestor of some element which `class` attr is `impl`.
+  - `//h1[@class="fqn"]/span[1]/a[last()]/@class` matches a value of
+    `class` attribute in the last `a` element (can be followed by more
+    elements that are not `a`) inside the first `span` in the `h1` with
+    a class of `fqn`. Note that there cannot be no additional elements
+    between them due to the use of `/` instead of `//`.
+
+  Do not try to use non-absolute paths, it won't work due to the flawed
+  ElementTree implementation. The script rejects them.
+
+  For the text matches (i.e. paths not ending with `@attr`), any
+  subelements are flattened into one string; this is handy for ignoring
+  highlights for example. If you want to simply check the presence of
+  given node or attribute, use an empty string (`""`) as a `PATTERN`.
+
+All conditions can be negated with `!`. `@!has foo/type.NoSuch.html`
+checks if the given file does not exist, for example.
+
+"""
+
+import sys
+import os.path
+import re
+import shlex
+from collections import namedtuple
+from HTMLParser import HTMLParser
+from xml.etree import cElementTree as ET
+
+# &larrb;/&rarrb; are not in HTML 4 but are in HTML 5
+from htmlentitydefs import entitydefs
+entitydefs['larrb'] = u'\u21e4'
+entitydefs['rarrb'] = u'\u21e5'
+
+# "void elements" (no closing tag) from the HTML Standard section 12.1.2
+VOID_ELEMENTS = set(['area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input', 'keygen',
+                     'link', 'menuitem', 'meta', 'param', 'source', 'track', 'wbr'])
+
+# simplified HTML parser.
+# this is possible because we are dealing with very regular HTML from rustdoc;
+# we only have to deal with i) void elements and ii) empty attributes.
+class CustomHTMLParser(HTMLParser):
+    def __init__(self, target=None):
+        HTMLParser.__init__(self)
+        self.__builder = target or ET.TreeBuilder()
+    def handle_starttag(self, tag, attrs):
+        attrs = dict((k, v or '') for k, v in attrs)
+        self.__builder.start(tag, attrs)
+        if tag in VOID_ELEMENTS: self.__builder.end(tag)
+    def handle_endtag(self, tag):
+        self.__builder.end(tag)
+    def handle_startendtag(self, tag, attrs):
+        attrs = dict((k, v or '') for k, v in attrs)
+        self.__builder.start(tag, attrs)
+        self.__builder.end(tag)
+    def handle_data(self, data):
+        self.__builder.data(data)
+    def handle_entityref(self, name):
+        self.__builder.data(entitydefs[name])
+    def handle_charref(self, name):
+        code = int(name[1:], 16) if name.startswith(('x', 'X')) else int(name, 10)
+        self.__builder.data(unichr(code).encode('utf-8'))
+    def close(self):
+        HTMLParser.close(self)
+        return self.__builder.close()
+
+Command = namedtuple('Command', 'negated cmd args lineno')
+
+LINE_PATTERN = re.compile(r'(?<=(?<!\S)@)(?P<negated>!?)(?P<cmd>[A-Za-z]+(?:-[A-Za-z]+)*)(?P<args>.*)$')
+def get_commands(template):
+    with open(template, 'rUb') as f:
+        for lineno, line in enumerate(f):
+            m = LINE_PATTERN.search(line.rstrip('\r\n'))
+            if not m: continue
+
+            negated = (m.group('negated') == '!')
+            cmd = m.group('cmd')
+            args = m.group('args')
+            if args and not args[:1].isspace():
+                raise RuntimeError('Invalid template syntax at line {}'.format(lineno+1))
+            args = shlex.split(args)
+            yield Command(negated=negated, cmd=cmd, args=args, lineno=lineno+1)
+
+def _flatten(node, acc):
+    if node.text: acc.append(node.text)
+    for e in node:
+        _flatten(e, acc)
+        if e.tail: acc.append(e.tail)
+
+def flatten(node):
+    acc = []
+    _flatten(node, acc)
+    return ''.join(acc)
+
+def normalize_xpath(path):
+    if path.startswith('//'):
+        return '.' + path # avoid warnings
+    elif path.startswith('.//'):
+        return path
+    else:
+        raise RuntimeError('Non-absolute XPath is not supported due to \
+                            the implementation issue.')
+
+class CachedFiles(object):
+    def __init__(self, root):
+        self.root = root
+        self.files = {}
+        self.trees = {}
+        self.last_path = None
+
+    def resolve_path(self, path):
+        if path != '-':
+            path = os.path.normpath(path)
+            self.last_path = path
+            return path
+        elif self.last_path is None:
+            raise RuntimeError('Tried to use the previous path in the first command')
+        else:
+            return self.last_path
+
+    def get_file(self, path):
+        path = self.resolve_path(path)
+        try:
+            return self.files[path]
+        except KeyError:
+            try:
+                with open(os.path.join(self.root, path)) as f:
+                    data = f.read()
+            except Exception as e:
+                raise RuntimeError('Cannot open file {!r}: {}'.format(path, e))
+            else:
+                self.files[path] = data
+                return data
+
+    def get_tree(self, path):
+        path = self.resolve_path(path)
+        try:
+            return self.trees[path]
+        except KeyError:
+            try:
+                f = open(os.path.join(self.root, path))
+            except Exception as e:
+                raise RuntimeError('Cannot open file {!r}: {}'.format(path, e))
+            try:
+                with f:
+                    tree = ET.parse(f, CustomHTMLParser())
+            except Exception as e:
+                raise RuntimeError('Cannot parse an HTML file {!r}: {}'.format(path, e))
+            else:
+                self.trees[path] = tree
+                return self.trees[path]
+
+def check_string(data, pat, regexp):
+    if not pat:
+        return True # special case a presence testing
+    elif regexp:
+        return re.search(pat, data) is not None
+    else:
+        data = ' '.join(data.split())
+        pat = ' '.join(pat.split())
+        return pat in data
+
+def check_tree_attr(tree, path, attr, pat, regexp):
+    path = normalize_xpath(path)
+    ret = False
+    for e in tree.findall(path):
+        try:
+            value = e.attrib[attr]
+        except KeyError:
+            continue
+        else:
+            ret = check_string(value, pat, regexp)
+            if ret: break
+    return ret
+
+def check_tree_text(tree, path, pat, regexp):
+    path = normalize_xpath(path)
+    ret = False
+    for e in tree.findall(path):
+        try:
+            value = flatten(e)
+        except KeyError:
+            continue
+        else:
+            ret = check_string(value, pat, regexp)
+            if ret: break
+    return ret
+
+def check(target, commands):
+    cache = CachedFiles(target)
+    for c in commands:
+        if c.cmd == 'has' or c.cmd == 'matches': # string test
+            regexp = (c.cmd == 'matches')
+            if len(c.args) == 1 and not regexp: # @has <path> = file existence
+                try:
+                    cache.get_file(c.args[0])
+                    ret = True
+                except RuntimeError:
+                    ret = False
+            elif len(c.args) == 2: # @has/matches <path> <pat> = string test
+                ret = check_string(cache.get_file(c.args[0]), c.args[1], regexp)
+            elif len(c.args) == 3: # @has/matches <path> <pat> <match> = XML tree test
+                tree = cache.get_tree(c.args[0])
+                pat, sep, attr = c.args[1].partition('/@')
+                if sep: # attribute
+                    ret = check_tree_attr(cache.get_tree(c.args[0]), pat, attr, c.args[2], regexp)
+                else: # normalized text
+                    pat = c.args[1]
+                    if pat.endswith('/text()'): pat = pat[:-7]
+                    ret = check_tree_text(cache.get_tree(c.args[0]), pat, c.args[2], regexp)
+            else:
+                raise RuntimeError('Invalid number of @{} arguments \
+                                    at line {}'.format(c.cmd, c.lineno))
+
+        elif c.cmd == 'valid-html':
+            raise RuntimeError('Unimplemented @valid-html at line {}'.format(c.lineno))
+
+        elif c.cmd == 'valid-links':
+            raise RuntimeError('Unimplemented @valid-links at line {}'.format(c.lineno))
+
+        else:
+            raise RuntimeError('Unrecognized @{} at line {}'.format(c.cmd, c.lineno))
+
+        if ret == c.negated:
+            raise RuntimeError('@{}{} check failed at line {}'.format('!' if c.negated else '',
+                                                                      c.cmd, c.lineno))
+
+if __name__ == '__main__':
+    if len(sys.argv) < 3:
+        print >>sys.stderr, 'Usage: {} <doc dir> <template>'.format(sys.argv[0])
+        raise SystemExit(1)
+    else:
+        check(sys.argv[1], get_commands(sys.argv[2]))
+