tests: add a tool for mass updates

When we update some output format, too many adjustements must be made
by hand.  This script updates most tests based on the actual output
made during the tests.

* build-aux/update-test: New.

README-hacking

@@ -195,6 +195,11 @@ update.
 ** make check
 Use liberally.
 
+** Updating the expectations
+Sometimes some changes have a large impact on the test suite (e.g., when we
+added the "[-Wother]" part to all the warnings).  Part of the update can be
+done with a crude tool: tests/update-test.  Read it for more information.
+
 ** TESTSUITEFLAGS
 
 To run just the testsuite (not the tests related to the examples), run `make

build-aux/update-test

@@ -0,0 +1,93 @@
+#! /usr/bin/env python
+
+# usage:
+# update-test _build/8d/tests/testsuite.dir/*.testsuite.log
+
+import argparse
+import os
+import re
+
+
+def getargs():
+    p = argparse.ArgumentParser(description='Update test cases.')
+    opt = p.add_argument
+    opt('tests', metavar='test', nargs='+', type=str, default=None,
+        help='test files to update')
+    opt('-v', '--verbose', action='store_true',
+        help='Be verbose')
+    return p.parse_args()
+
+args = getargs()
+subst = dict()
+
+
+def log(*args_):
+    if args.verbose:
+        print(*args_)
+
+
+def contents(file):
+    '''The contents of a file.'''
+    log(file)
+    f = open(file)
+    return f.read()
+
+
+def diff_to_re(match):
+    '''Convert a portion of patch into a regex substitution to perform.
+    No longer used, we now use the expected/effective parts.
+    '''
+    frm = []
+    to = []
+    is_diff = False
+    for l in match.group(1).splitlines():
+        print(l)
+        # t in [-+ ]
+        t = l[0]
+        l = l[1:]
+        if t in ['-', ' ']:
+            is_diff = True
+            frm.append(l)
+        if t in ['+', ' ']:
+            is_diff = True
+            to.append(l)
+    if is_diff:
+        frm = "\n".join(frm)
+        to = "\n".join(to)
+        subst[frm] = to
+
+
+def update(at_file, logfile):
+    test = contents(at_file)
+    if os.path.isfile(logfile):
+        log("LOG: ", logfile)
+        l = contents(logfile)
+        log("LOG: ", l)
+        global subst
+        subst = {}
+        re.sub(r'(?:^@@.*\n)((?:^[-+ ].*\n)+)',
+               diff_to_re, l, flags = re.MULTILINE)
+        print(subst)
+        if subst:
+            # Turn "subst{frm} -> to" into a large RE.
+            frm = '|'.join([re.escape(x) for x in subst])
+            log("FROM:", frm)
+            test = re.sub("(" + frm + ")",
+                          lambda m: subst[m.group(1)],
+                          test, flags=re.MULTILINE)
+    open(at_file, 'w').write(test)
+
+
+def process(logfile):
+    log = contents(logfile)
+    # Look for the file to update.
+    m = re.search(r'^\d+\. (\w+\.at):\d+: ', log, re.MULTILINE)
+    if not m:
+        return
+    at_file = 'tests/' + m.group(1)
+    print(at_file)
+    update(at_file, logfile)
+
+for t in args.tests:
+    log("FILE:", t)
+    process(t)