checks

check50 API

Checks

• diff(f1, f2)
  • Checks two files against each other; returns a boolean, True if the two files are different
• require(paths)
  • Asserts that all paths passed into the function exist, raises an Error otherwise
• hash(filename)
  • Returns the SHA-256 hash of the file
• spawn(cmd, env=None)
  • Runs the command cmd with environment variables specified by env, returns a Child
• add(cmd, paths)
  • Includes each of paths in checks directory
• append_code(filename, codefile)
  • Appends the contents of filename to the end of codefile
• replace_fn(old_fn, new_fn, filename)
  • Replaces C function calls to old_fn with function calls to new_fn in assembly file filename

Child

• stdin(line, prompt=True, timeout=3)
  • Passes in the line of input (or passes EOF if line is EOF)
  • If prompt is True, asserts that some textual prompt should be displayed first before passing in stdin, and will wait up to timeout seconds for the prompt
• stdout(output=None, str_output=None, timeout=3)
  • If output is None, waits timeout seconds for program to terminate, and then returns the output (stdout and stderr)
  • Otherwise, asserts that the program’s output will match the regex output
  • If output is a file, rather than a regex, then the method asserts that the output matches the file exactly
  • str_output is the human-friendly version of the output regex which will be displayed in error messages to the student
• reject(timeout=3)
  • Asserts that the student’s program will reject the previously provided input; in other words, asserts that the program provides a textual prompt (within timeout seconds) and then waits for stdin
• exit(code=None, timeout=3)
  • waits timeout seconds for the program to terminate
  • If code is None, returns the exit code
  • If code isn’t None, asserts that the program exits with code code
• wait(timeout=3)
  • Waits timeout seconds for program to terminate, raises an error if it doesn’t
• kill()
  • Terminates the process

Error

• __init__(rationale=None, helpers=None, result=Checks.FAIL)
  • When raised, the check ends with the result
  • rationale is the reason why the check failed (and should be either a str or a Mismatch)
  • helpers is a line of advice for how the student might be able to fix their problem
  • result can be PASS, FAIL, or SKIP

Mismatch

• __init__(expected, actual)
  • Represents a type of rationale that can be passed to an Error. Used to indicate that we expected output expected, but got output actual

File

• __init__(filename)
  • Represents a file whose name is filename
• read()
  • Returns the contents of the file

Decorators

• @check(dependency)
  • Defines a check to run: will only run if dependency passes, and will use its side-effects
• @valgrind
  • Checks for memory errors during check