Fix crash of guess_format on valid empty jbsq file

CHANGELOG.md

@@ -5,8 +5,12 @@ each version
 
 Format based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
-I try to follow [Semantic Versioning](https://semver.org/spec/v2.0.0.html),
-sometimes.
+I try to follow [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## v2.0.1
+### Fixed
+- `guess_format()` would raise an exception when called on a specially crafted
+  empty jbsq file, not anymore !
 
 ## v2.0.0
 ### BREAKING CHANGE

jubeatools/formats/guess.py

@@ -1,6 +1,8 @@
 import json
 import re
+from functools import wraps
 from pathlib import Path
+from typing import Any, Callable, Type
 
 from .format_names import Format
 
@@ -108,17 +110,29 @@ def recognize_jubeat_analyser_format(path: Path) -> Format:
         raise ValueError("Unrecognized file format")
 
 
+def false_if_raises(
+    *exceptions: Type[Exception],
+) -> Callable[[Callable[..., bool]], Callable[..., bool]]:
+    def decorator(f: Callable[..., bool]) -> Callable[..., bool]:
+        @wraps(f)
+        def wrapper(*a: Any, **kw: Any) -> bool:
+            try:
+                return f(*a, **kw)
+            except Exception as e:
+                if exceptions and not isinstance(e, exceptions):
+                    raise
+                else:
+                    return False
+
+        return wrapper
+
+    return decorator
+
+
+@false_if_raises(UnicodeDecodeError, StopIteration)
 def looks_like_eve(path: Path) -> bool:
     with path.open(encoding="ascii") as f:
-        try:
-            line = f.readline()
-        except UnicodeDecodeError:
-            return False
-
-        if line.strip():
-            return looks_like_eve_line(next(f))
-
-    return False
+        return looks_like_eve_line(f.readline())
 
 
 EVE_COMMANDS = {
@@ -154,5 +168,6 @@ def looks_like_eve_line(line: str) -> bool:
 
 
 def looks_like_jbsq(path: Path) -> bool:
-    magic = path.open(mode="rb").read(4)
-    return magic in (b"IJBQ", b"IJSQ", b"JBSQ")
+    with path.open(mode="rb") as f:
+        magic = f.read(4)
+        return magic in (b"IJBQ", b"IJSQ", b"JBSQ")

jubeatools/formats/konami/jbsq/tests/example1.py

@@ -0,0 +1,23 @@
+from decimal import Decimal
+from fractions import Fraction
+
+from jubeatools.song import *
+
+data = Song(
+    metadata=Metadata(
+        title=None, artist=None, audio=None, cover=None, preview=None, preview_file=None
+    ),
+    charts={
+        "BSC": Chart(
+            level=Decimal("0"),
+            timing=Timing(
+                events=(BPMEvent(time=Fraction(0, 1), BPM=Decimal("288.11")),),
+                beat_zero_offset=Decimal("0.04"),
+            ),
+            hakus=set(),
+            notes=[],
+        )
+    },
+    common_timing=None,
+    common_hakus=None,
+)

jubeatools/formats/konami/jbsq/tests/test_jbsq.py

@@ -1,13 +1,14 @@
 from enum import Enum
 
-from hypothesis import given
+from hypothesis import example, given
 
 from jubeatools import song
 from jubeatools.formats import Format
 from jubeatools.formats.konami.testutils import eve_compatible_song
 from jubeatools.testutils.test_patterns import dump_and_load, dump_and_load_then_compare
 
-from .construct import jbsq
+from ..construct import jbsq
+from . import example1
 
 
 @given(eve_compatible_song())
@@ -21,6 +22,7 @@ def test_that_full_chart_roundtrips(song: song.Song) -> None:
 
 
 @given(eve_compatible_song())
+@example(example1.data)
 def test_that_difficulty_name_is_loaded_properly(original_song: song.Song) -> None:
     recovered_song = dump_and_load(
         Format.JBSQ,

poetry.lock

@@ -22,7 +22,7 @@ tests_no_zope = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>
 
 [[package]]
 name = "autoflake"
-version = "1.5.3"
+version = "1.6.0"
 description = "Removes unused imports and unused variables"
 category = "dev"
 optional = false
@@ -30,11 +30,11 @@ python-versions = ">=3.7"
 
 [package.dependencies]
 pyflakes = ">=1.1.0"
-toml = ">=0.10.2"
+tomli = {version = ">=2.0.1", markers = "python_version < \"3.11\""}
 
 [[package]]
 name = "autoimport"
-version = "1.2.2"
+version = "1.2.3"
 description = "Autoimport missing python libraries."
 category = "dev"
 optional = false
@@ -137,7 +137,7 @@ pyflakes = ">=2.3.0,<2.4.0"
 
 [[package]]
 name = "hypothesis"
-version = "6.54.5"
+version = "6.54.6"
 description = "A library for property-based testing"
 category = "dev"
 optional = false
@@ -201,7 +201,7 @@ toml = ">=0.10.2,<0.11.0"
 
 [[package]]
 name = "marshmallow"
-version = "3.17.1"
+version = "3.18.0"
 description = "A lightweight library for converting complex datatypes to and from native Python datatypes."
 category = "main"
 optional = false
@@ -211,9 +211,9 @@ python-versions = ">=3.7"
 packaging = ">=17.0"
 
 [package.extras]
-dev = ["pytest", "pytz", "simplejson", "mypy (==0.971)", "flake8 (==5.0.4)", "flake8-bugbear (==22.8.22)", "pre-commit (>=2.4,<3.0)", "tox"]
+dev = ["pytest", "pytz", "simplejson", "mypy (==0.971)", "flake8 (==5.0.4)", "flake8-bugbear (==22.9.11)", "pre-commit (>=2.4,<3.0)", "tox"]
 docs = ["sphinx (==5.1.1)", "sphinx-issues (==3.0.1)", "alabaster (==0.7.12)", "sphinx-version-warning (==1.1.2)", "autodocsumm (==0.2.9)"]
-lint = ["mypy (==0.971)", "flake8 (==5.0.4)", "flake8-bugbear (==22.8.22)", "pre-commit (>=2.4,<3.0)"]
+lint = ["mypy (==0.971)", "flake8 (==5.0.4)", "flake8-bugbear (==22.9.11)", "pre-commit (>=2.4,<3.0)"]
 tests = ["pytest", "pytz", "simplejson"]
 
 [[package]]
@@ -362,7 +362,7 @@ python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [[package]]
 name = "pydantic"
-version = "1.10.1"
+version = "1.10.2"
 description = "Data validation and settings management using python type hints"
 category = "dev"
 optional = false
@@ -559,10 +559,7 @@ content-hash = "a94015b3d8ca8a0e27556df0eb4697f7b4765510b89b49466ffc2a1a92174616
 atomicwrites = []
 attrs = []
 autoflake = []
-autoimport = [
-    {file = "autoimport-1.2.2-py3-none-any.whl", hash = "sha256:cf8982a621df199eff0e88f3f1190dc4f72093395f6bf478e544fac10217f160"},
-    {file = "autoimport-1.2.2.tar.gz", hash = "sha256:ae58d93b1b71529f78bcf06733e60170600620c903740f5745f928cc8f1243f3"},
-]
+autoimport = []
 black = []
 click = [
     {file = "click-8.1.3-py3-none-any.whl", hash = "sha256:bb4d8133cb15a609f44e8213d9b391b0809795062913b383c62be0ee95b1db48"},