Refactor main API (#6)

Separate argument creation from execution. This will allow us to
access the list of files before any checks are run on them.

src/rapids_pre_commit_hooks/lint.py

@@ -194,11 +194,9 @@ def _calculate_lines(self):
         self.lines.append((line_begin, line_end))
 
 
-class LintMain(contextlib.AbstractContextManager):
-    def __init__(self):
-        self.argparser = argparse.ArgumentParser()
-        self.argparser.add_argument("--fix", action="store_true")
-        self.argparser.add_argument("file", nargs="+")
+class ExecutionContext(contextlib.AbstractContextManager):
+    def __init__(self, args):
+        self.args = args
         self.checks = []
 
     def add_check(self, check):
@@ -210,18 +208,16 @@ def __exit__(self, exc_type, exc_value, traceback):
 
         warnings = False
 
-        args = self.argparser.parse_args()
-
-        for file in args.file:
+        for file in self.args.files:
             with open(file) as f:
                 content = f.read()
 
             linter = Linter(file, content)
             for check in self.checks:
-                check(linter, args)
+                check(linter, self.args)
 
-            linter.print_warnings(args.fix)
-            if args.fix:
+            linter.print_warnings(self.args.fix)
+            if self.args.fix:
                 fix = linter.fix()
                 if fix != content:
                     with open(file, "w") as f:
@@ -232,3 +228,15 @@ def __exit__(self, exc_type, exc_value, traceback):
 
         if warnings:
             exit(1)
+
+
+class LintMain:
+    context_class = ExecutionContext
+
+    def __init__(self):
+        self.argparser = argparse.ArgumentParser()
+        self.argparser.add_argument("--fix", action="store_true")
+        self.argparser.add_argument("files", nargs="+", metavar="file")
+
+    def execute(self):
+        return self.context_class(self.argparser.parse_args())

src/rapids_pre_commit_hooks/shell/__init__.py

@@ -14,7 +14,7 @@
 
 import bashlex
 
-from ..lint import LintMain
+from ..lint import ExecutionContext, LintMain
 
 
 class LintVisitor(bashlex.ast.nodevisitor):
@@ -26,9 +26,9 @@ def add_warning(self, pos, msg):
         return self.linter.add_warning(pos, msg)
 
 
-class ShellMain(LintMain):
-    def __init__(self):
-        super().__init__()
+class ShellExecutionContext(ExecutionContext):
+    def __init__(self, args):
+        super().__init__(args)
         self.visitors = []
         self.add_check(self.check_shell)
 
@@ -42,3 +42,7 @@ def check_shell(self, linter, args):
             visitor = cls(linter, args)
             for part in parts:
                 visitor.visit(part)
+
+
+class ShellMain(LintMain):
+    context_class = ShellExecutionContext

src/rapids_pre_commit_hooks/shell/verify_conda_yes.py

@@ -74,8 +74,9 @@ def visitcommand(self, n, parts):
 
 
 def main():
-    with ShellMain() as m:
-        m.add_visitor_class(VerifyCondaYesVisitor)
+    m = ShellMain()
+    with m.execute() as ctx:
+        ctx.add_visitor_class(VerifyCondaYesVisitor)
 
 
 if __name__ == "__main__":

test/rapids_pre_commit_hooks/test_lint.py

@@ -152,16 +152,20 @@ def the_check(self, linter, args):
 
     def test_no_warnings_no_fix(self, hello_world_file, capsys):
         with MockArgv("check-test", "--check-test", hello_world_file.name):
-            with LintMain() as m:
-                m.argparser.add_argument("--check-test", action="store_true")
+            m = LintMain()
+            m.argparser.add_argument("--check-test", action="store_true")
+            with m.execute():
+                pass
         assert hello_world_file.read() == "Hello world!"
         captured = capsys.readouterr()
         assert captured.out == ""
 
     def test_no_warnings_fix(self, hello_world_file, capsys):
         with MockArgv("check-test", "--check-test", "--fix", hello_world_file.name):
-            with LintMain() as m:
-                m.argparser.add_argument("--check-test", action="store_true")
+            m = LintMain()
+            m.argparser.add_argument("--check-test", action="store_true")
+            with m.execute():
+                pass
         assert hello_world_file.read() == "Hello world!"
         captured = capsys.readouterr()
         assert captured.out == ""
@@ -170,9 +174,10 @@ def test_warnings_no_fix(self, hello_world_file, capsys):
         with MockArgv(
             "check-test", "--check-test", hello_world_file.name
         ), pytest.raises(SystemExit, match=r"^1$"):
-            with LintMain() as m:
-                m.argparser.add_argument("--check-test", action="store_true")
-                m.add_check(self.the_check)
+            m = LintMain()
+            m.argparser.add_argument("--check-test", action="store_true")
+            with m.execute() as ctx:
+                ctx.add_check(self.the_check)
         assert hello_world_file.read() == "Hello world!"
         captured = capsys.readouterr()
         assert (
@@ -204,9 +209,10 @@ def test_warnings_fix(self, hello_world_file, capsys):
         with MockArgv(
             "check-test", "--check-test", "--fix", hello_world_file.name
         ), pytest.raises(SystemExit, match=r"^1$"):
-            with LintMain() as m:
-                m.argparser.add_argument("--check-test", action="store_true")
-                m.add_check(self.the_check)
+            m = LintMain()
+            m.argparser.add_argument("--check-test", action="store_true")
+            with m.execute() as ctx:
+                ctx.add_check(self.the_check)
         assert hello_world_file.read() == "Good bye, world!"
         captured = capsys.readouterr()
         assert (
@@ -242,9 +248,10 @@ def test_multiple_files(self, hello_world_file, hello_file, capsys):
             hello_world_file.name,
             hello_file.name,
         ), pytest.raises(SystemExit, match=r"^1$"):
-            with LintMain() as m:
-                m.argparser.add_argument("--check-test", action="store_true")
-                m.add_check(self.the_check)
+            m = LintMain()
+            m.argparser.add_argument("--check-test", action="store_true")
+            with m.execute() as ctx:
+                ctx.add_check(self.the_check)
         assert hello_world_file.read() == "Good bye, world!"
         assert hello_file.read() == "Good bye!"
         captured = capsys.readouterr()