Added mktemp method to FileProxy (fixes #121) (#124)

* added method api

* generated command

* implemented mktemp

* bug fix: missing import

* added basic test_mktemp

* test suffixes

* bug fix: use --suffix and --tmpdir

* added prefix test

* added test for specified dir

* added test for non-existent dir

* bug fix: check directory existence

* trailing space

* bug fix: use prefix to build template

Author: ChrisTimperley

src/rozzy/proxy/file.py

@@ -1,6 +1,10 @@
+# -*- coding: utf-8 -*-
+"""
+This file implements a proxy for accessing container file systems.
+"""
 __all__ = ('FileProxy',)
 
-from typing import List, Union, overload
+from typing import List, Union, Optional, overload
 from typing_extensions import Literal
 import os
 import shlex
@@ -337,3 +341,45 @@ def rmtree(self, d: str) -> None:
         code, output, duration = self.__shell.execute(cmd)
         if code != 0:
             raise OSError(f"failed to remove directory tree: {d}")
+
+    def mktemp(self,
+               suffix: Optional[str] = None,
+               prefix: Optional[str] = None,
+               dirname: Optional[str] = None
+               ) -> str:
+        """Creates a temporary file.
+
+        Parameters
+        ----------
+        suffix: str, optional
+            an optional suffix for the filename.
+        prefix: str, optional
+            an optional prefix for the filename.
+        dirname: str, optional
+            if specified, the temporary file will be created in the given
+            directory.
+
+        Raises
+        ------
+        FileNotFoundError:
+            if specified directory does not exist.
+        OSError:
+            if the temporary file could not be constructed.
+        """
+        template = shlex.quote(f"{prefix if prefix else 'tmp'}.XXXXXXXXXX")
+        cmd_parts = ['mktemp', template]
+        if suffix:
+            cmd_parts += ['--suffix', shlex.quote(suffix)]
+        if dirname:
+            cmd_parts += ['-p', shlex.quote(dirname)]
+            if not self.isdir(dirname):
+                m = f'directory does not exist: {dirname}'
+                raise FileNotFoundError(m)
+        cmd = ' '.join(cmd_parts)
+
+        code, output, duration = self.__shell.execute(cmd)
+        # TODO capture context
+        if code != 0:
+            raise OSError(f"failed to create temporary directory")
+
+        return output

test/test_file.py

@@ -321,3 +321,34 @@ def test_write():
         # write to a file that belongs to a non-existent directory
         with pytest.raises(FileNotFoundError):
             files.write('/tmp/bar/bork', 'code things')
+
+
+def test_mktemp():
+    with build_file_proxy() as files:
+        # create a temporary file
+        fn = files.mktemp()
+        assert files.isfile(fn)
+
+        # use specified dir
+        d = '/boop'
+        files.makedirs(d, exist_ok=True)
+        assert files.isdir(d)
+        fn = files.mktemp(dirname=d)
+        assert os.path.dirname(fn) == d
+        assert files.isfile(fn)
+
+        # use non-existent dir
+        with pytest.raises(FileNotFoundError):
+            d = '/idontexist'
+            assert not files.isdir(d)
+            files.mktemp(dirname=d)
+
+        # add suffix
+        fn = files.mktemp(suffix='.foo')
+        assert fn.endswith('.foo')
+        assert files.isfile(fn)
+
+        # add prefix
+        fn = files.mktemp(prefix='foo')
+        assert os.path.basename(fn).startswith('foo')
+        assert files.isfile(fn)