charmcraft/jujuignore.py: Allow extending the list of patterns. (#99)

This adds the ability for JujuIgnore to pull in the default ignores and extend them with .jujuignore contents.

I don't have tests around the walk functionality, but I figured I would leave it in there to show you how I was thinking it would look.

charmcraft/commands/build.py

@@ -25,6 +25,7 @@
 import yaml
 
 from charmcraft.cmdbase import BaseCommand, CommandError
+from charmcraft.jujuignore import JujuIgnore, default_juju_ignore
 from .utils import make_executable
 
 logger = logging.getLogger(__name__)
@@ -87,6 +88,7 @@ def __init__(self, args):
         self.requirement_paths = args['requirement']
 
         self.buildpath = self.charmdir / BUILD_DIRNAME
+        self.ignore_rules = self._load_juju_ignore()
 
     def run(self):
         """Main building process."""
@@ -110,11 +112,20 @@ def _link_to_buildpath(self, srcpath):
         destpath.symlink_to(srcpath)
         return destpath
 
+    def _load_juju_ignore(self):
+        ignore = JujuIgnore(default_juju_ignore)
+        path = self.charmdir / '.jujuignore'
+        if path.exists():
+            with path.open('r', encoding='utf-8') as ignores:
+                ignore.extend_patterns(ignores)
+        return ignore
+
     def handle_code(self):
         """Handle basic files and the charm source code."""
         # basic files
         logger.debug("Linking in basic files and charm code")
         self._link_to_buildpath(self.charmdir / CHARM_METADATA)
+
         for fn in CHARM_OPTIONAL:
             path = self.charmdir / fn
             if path.exists():

charmcraft/jujuignore.py

@@ -151,7 +151,11 @@ def __init__(self, patterns: typing.Iterable[str]):
         self._matchers = []
         self._compile_from(patterns)
 
-    def _compile_from(self, patterns):
+    def extend_patterns(self, patterns: typing.Iterable[str]) -> None:
+        """Add more patterns to the ignore list."""
+        self._compile_from(patterns)
+
+    def _compile_from(self, patterns: typing.Iterable[str]):
         for line_num, rule in enumerate(patterns, 1):
             orig_rule = rule
             rule = rule.lstrip().rstrip('\r\n')

tests/commands/test_build.py

@@ -894,3 +894,43 @@ def test_build_package_name(tmp_path, monkeypatch):
     zipname = builder.handle_package()
 
     assert zipname == "name-from-metadata.charm"
+
+
+def test_builder_without_jujuignore(tmp_path):
+    """Without a .jujuignore we still have a default set of ignores"""
+    build_dir = tmp_path / BUILD_DIRNAME
+    build_dir.mkdir()
+
+    builder = Builder({
+        'from': tmp_path,
+        'entrypoint': 'whatever',
+        'requirement': [],
+    })
+    ignore = builder._load_juju_ignore()
+    assert ignore.match('/.git', is_dir=True)
+    assert ignore.match('/build', is_dir=True)
+    assert not ignore.match('myfile.py', is_dir=False)
+
+
+def test_builder_with_jujuignore(tmp_path):
+    """With a .jujuignore we will include additional ignores."""
+    build_dir = tmp_path / BUILD_DIRNAME
+    build_dir.mkdir()
+    with (tmp_path / '.jujuignore').open('w', encoding='utf-8') as ignores:
+        ignores.write(
+            '*.py\n'
+            '/h\xef.txt\n'
+        )
+
+    builder = Builder({
+        'from': tmp_path,
+        'entrypoint': 'whatever',
+        'requirement': [],
+    })
+    ignore = builder._load_juju_ignore()
+    assert ignore.match('/.git', is_dir=True)
+    assert ignore.match('/build', is_dir=True)
+    assert ignore.match('myfile.py', is_dir=False)
+    assert not ignore.match('hi.txt', is_dir=False)
+    assert ignore.match('h\xef.txt', is_dir=False)
+    assert not ignore.match('myfile.c', is_dir=False)

tests/test_jujuignore.py

@@ -397,3 +397,12 @@ def test_special_chars_in_brackets():
         ['foob.py', 'fooc.py', 'foo^.py'],
         [r'foo.py', r'fooa.py', r'fooa^.py'],
     )
+
+
+def test_extend_patterns():
+    ignore = jujuignore.JujuIgnore(['foo'])
+    assert ignore.match('foo', is_dir=False)
+    assert not ignore.match('bar', is_dir=False)
+    ignore.extend_patterns(['bar'])
+    assert ignore.match('foo', is_dir=False)
+    assert ignore.match('bar', is_dir=False)