Update littlecheck

This allows:

- Running scripts via shebang (not important here)
- Progress output (so we can ditch more of our run script)
- Context (only after, for now) - this is important if there is a test failure

build_tools/littlecheck.py

@@ -27,6 +27,10 @@ class Config(object):
         self.verbose = False
         # Whether output gets ANSI colorization.
         self.colorize = False
+        # Whether to show which file was tested.
+        self.progress = False
+        # How many after lines to print
+        self.after = 5
 
     def colors(self):
         """ Return a dictionary mapping color names to ANSI escapes """
@@ -112,13 +116,16 @@ class RunCmd(object):
 
 
 class TestFailure(object):
-    def __init__(self, line, check, testrun):
+    def __init__(self, line, check, testrun, after = None):
         self.line = line
         self.check = check
         self.testrun = testrun
         self.error_annotation_line = None
+        # The output that comes *after* the failure.
+        self.after = after
 
     def message(self):
+        afterlines = self.testrun.config.after
         fields = self.testrun.config.colors()
         fields["name"] = self.testrun.name
         fields["subbed_command"] = self.testrun.subbed_command
@@ -139,7 +146,8 @@ class TestFailure(object):
                     "check_type": self.check.type,
                 }
             )
-        fmtstrs = ["{RED}Failure{RESET} in {name}:", ""]
+        filemsg = "" if self.testrun.config.progress else " in {name}"
+        fmtstrs = ["{RED}Failure{RESET}" + filemsg + ":", ""]
         if self.line and self.check:
             fmtstrs += [
                 "  The {check_type} on line {input_lineno} wants:",
@@ -171,6 +179,12 @@ class TestFailure(object):
                 "  additional output on stderr:{error_annotation_lineno}:",
                 "    {BOLD}{error_annotation}{RESET}",
             ]
+        if self.after:
+            fields["additional_output"] = "    ".join(self.after[:afterlines])
+            fmtstrs += [
+                "  additional output:",
+                "    {BOLD}{additional_output}{RESET}",
+                ]
         fmtstrs += ["  when running command:", "    {subbed_command}"]
         return "\n".join(fmtstrs).format(**fields)
 
@@ -194,7 +208,9 @@ def perform_substitution(input_str, subs):
         for key, replacement in subs_ordered:
             if text.startswith(key):
                 return replacement + text[len(key) :]
-        raise CheckerError("Unknown substitution: " + m.group(0))
+        # No substitution found, so we default to running it as-is,
+        # which will end up running it via $PATH.
+        return text
 
     return re.sub(r"%(%|[a-zA-Z0-9_-]+)", subber, input_str)
 
@@ -224,7 +240,9 @@ class TestRun(object):
                 lineq.pop()
             else:
                 # Failed to match.
-                return TestFailure(line, check, self)
+                lineq.pop()
+                # Add context, ignoring empty lines.
+                return TestFailure(line, check, self, after = [line.text for line in lineq[::-1] if not line.is_empty_space()])
         # Drain empties.
         while lineq and lineq[-1].is_empty_space():
             lineq.pop()
@@ -258,6 +276,13 @@ class TestRun(object):
             close_fds=True,  # For Python 2.6 as shipped on RHEL 6
         )
         stdout, stderr = proc.communicate()
+        # HACK: This is quite cheesy: POSIX specifies that sh should return 127 for a missing command.
+        # Technically it's also possible to return it in other conditions.
+        # Practically, that's *probably* not going to happen.
+        status = proc.returncode
+        if status == 127:
+            raise CheckerError("Command could not be found: " + self.subbed_command)
+
         outlines = [
             Line(text, idx + 1, "stdout")
             for idx, text in enumerate(split_by_newlines(stdout))
@@ -343,7 +368,12 @@ class Checker(object):
         # Find run commands.
         self.runcmds = [RunCmd.parse(sl) for sl in group1s(RUN_RE)]
         if not self.runcmds:
-            raise CheckerError("No runlines ('# RUN') found")
+            # If no RUN command has been given, fall back to the shebang.
+            if lines[0].text.startswith("#!"):
+                # Remove the "#!" at the beginning, and the newline at the end.
+                self.runcmds = [RunCmd(lines[0].text[2:-1] + " %s", lines[0])]
+            else:
+                raise CheckerError("No runlines ('# RUN') found")
 
         # Find check cmds.
         self.outchecks = [
@@ -406,7 +436,22 @@ def get_argparse():
         action="append",
         default=[],
     )
+    parser.add_argument(
+        "-p",
+        "--progress",
+        action='store_true',
+        dest='progress',
+        help="Show the files to be checked",
+        default=False,
+    )
     parser.add_argument("file", nargs="+", help="File to check")
+    parser.add_argument(
+        "-A", "--after",
+        type=int,
+        help="How many non-empty lines of output after a failure to print (default: 5)",
+        action="store",
+        default=5,
+    )
     return parser
 
 
@@ -419,11 +464,19 @@ def main():
     success = True
     config = Config()
     config.colorize = sys.stdout.isatty()
+    config.progress = args.progress
+    fields = config.colors()
+    config.after = args.after
     for path in args.file:
+        fields["path"] = path
+        if config.progress:
+            print("Testing file {path} ... ".format(**fields), end='')
         subs = def_subs.copy()
         subs["s"] = path
         if not check_path(path, subs, config, TestFailure.print_message):
             success = False
+        elif config.progress:
+            print("{GREEN}ok{RESET}".format(**fields))
     sys.exit(0 if success else 1)