Add dedicated test for SSHRemoteIO symlink handling

datalad_ria/tests/test_ssh_remote_io.py

@@ -6,19 +6,41 @@
 
 @pytest.fixture(autouse=False, scope="function")
 def ssh_remoteio(ria_sshserver_setup, ria_sshserver):
+    """Yield a ``SSHRemoteIO`` instance matching the RIA server setup"""
     ssh = SSHRemoteIO(
         'ssh://{SSH_LOGIN}@{HOST}:{SSH_PORT}'.format(**ria_sshserver_setup)
     )
     yield ssh
 
 
+@pytest.fixture(autouse=False, scope="function")
+def ssh_remote_wdir(ssh_remoteio, ria_sshserver_setup):
+    """Like ``ssh_remoteio``, but also yields a working directory
+
+    It used ``mktemp -d`` on the remote end, and also remove the working
+    directory at the end.
+    """
+    sshpath = PurePosixPath(ria_sshserver_setup['SSH_PATH'])
+    out, err = ssh_remoteio.ssh(f'mktemp -d {sshpath}/sshremotewdir.XXXXXXXX')
+    # hopefully catch more stupid errors of unexpectedness
+    assert '/sshremotewdir' in out
+    wdir = PurePosixPath(out.rstrip('\n'))
+    yield ssh_remoteio, wdir
+    # clean up
+    # only run dangerous 'rm -rf' if needed
+    if ssh_remoteio.exists(wdir):
+        ssh_remoteio.ssh(f'echo rm -rf "{wdir}"')
+
+
 def test_SSHRemoteIO_read_file(ssh_remoteio):
     # basic smoke test, just login and use the abstraction to read a file
     etcpasswd = ssh_remoteio.read_file('/etc/passwd')
     # we can assume that the remote /etc/passwd file is not empty
     assert etcpasswd
 
 
+# this is not using `ssh_remote_wdir`, because we want to go manual
+# on all steps and have things break in a test, and not in a fixture
 def test_SSHRemoteIO_handledir(ssh_remoteio, ria_sshserver_setup):
     sshpath = PurePosixPath(ria_sshserver_setup['SSH_PATH'])
     targetdir = sshpath / 'testdir'
@@ -43,3 +65,16 @@ def test_SSHRemoteIO_handledir(ssh_remoteio, ria_sshserver_setup):
     # ssh_remoteio.remove(targetdir)
     ssh_remoteio.remove_dir(targetdir)
     assert not ssh_remoteio.exists(targetdir)
+
+
+def test_SSHRemoteIO_symlink(ssh_remote_wdir):
+    ssh_remoteio, targetdir = ssh_remote_wdir
+    targetfpath = targetdir / 'testfile'
+    assert not ssh_remoteio.exists(targetfpath)
+    ssh_remoteio.symlink('/etc/passwd', targetfpath)
+    assert ssh_remoteio.exists(targetfpath)
+    assert ssh_remoteio.read_file('/etc/passwd') \
+        == ssh_remoteio.read_file(targetfpath)
+    # verify that we can remove a symlink
+    ssh_remoteio.remove(targetfpath)
+    assert not ssh_remoteio.exists(targetfpath)