src/etc/generate-deriving-span-tests.py

#!/usr/bin/env python

"""
This script creates a pile of UI tests check that all the
derives have spans that point to the fields, rather than the
#[derive(...)] line.

sample usage: src/etc/generate-deriving-span-tests.py
"""

import os
import stat

TEST_DIR = os.path.abspath(
    os.path.join(os.path.dirname(__file__), "../test/ui/derives/")
)

TEMPLATE = """\
// This file was auto-generated using 'src/etc/generate-deriving-span-tests.py'

{error_deriving}
struct Error;
{code}
fn main() {{}}
"""

ENUM_STRING = """
#[derive({traits})]
enum Enum {{
   A(
     Error {errors}
     )
}}
"""
ENUM_STRUCT_VARIANT_STRING = """
#[derive({traits})]
enum Enum {{
   A {{
     x: Error {errors}
   }}
}}
"""
STRUCT_STRING = """
#[derive({traits})]
struct Struct {{
    x: Error {errors}
}}
"""
STRUCT_TUPLE_STRING = """
#[derive({traits})]
struct Struct(
    Error {errors}
);
"""

ENUM_TUPLE, ENUM_STRUCT, STRUCT_FIELDS, STRUCT_TUPLE = range(4)


def create_test_case(type, trait, super_traits, error_count):
    string = [
        ENUM_STRING,
        ENUM_STRUCT_VARIANT_STRING,
        STRUCT_STRING,
        STRUCT_TUPLE_STRING,
    ][type]
    all_traits = ",".join([trait] + super_traits)
    super_traits = ",".join(super_traits)
    error_deriving = "#[derive(%s)]" % super_traits if super_traits else ""

    errors = "\n".join("//~%s ERROR" % ("^" * n) for n in range(error_count))
    code = string.format(traits=all_traits, errors=errors)
    return TEMPLATE.format(error_deriving=error_deriving, code=code)


def write_file(name, string):
    test_file = os.path.join(TEST_DIR, "derives-span-%s.rs" % name)

    # set write permission if file exists, so it can be changed
    if os.path.exists(test_file):
        os.chmod(test_file, stat.S_IWUSR)

    with open(test_file, "w") as f:
        f.write(string)

    # mark file read-only
    os.chmod(test_file, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)


ENUM = 1
STRUCT = 2
ALL = STRUCT | ENUM

traits = {
    "Default": (STRUCT, [], 1),
    "FromPrimitive": (0, [], 0),  # only works for C-like enums
    "Decodable": (0, [], 0),  # FIXME: quoting gives horrible spans
    "Encodable": (0, [], 0),  # FIXME: quoting gives horrible spans
}

for trait, supers, errs in [
    ("Clone", [], 1),
    ("PartialEq", [], 2),
    ("PartialOrd", ["PartialEq"], 1),
    ("Eq", ["PartialEq"], 1),
    ("Ord", ["Eq", "PartialOrd", "PartialEq"], 1),
    ("Debug", [], 1),
    ("Hash", [], 1),
]:
    traits[trait] = (ALL, supers, errs)

for trait, (types, super_traits, error_count) in traits.items():

    def mk(ty, t=trait, st=super_traits, ec=error_count):
        return create_test_case(ty, t, st, ec)

    if types & ENUM:
        write_file(trait + "-enum", mk(ENUM_TUPLE))
        write_file(trait + "-enum-struct-variant", mk(ENUM_STRUCT))
    if types & STRUCT:
        write_file(trait + "-struct", mk(STRUCT_FIELDS))
        write_file(trait + "-tuple-struct", mk(STRUCT_TUPLE))