test(scp): Add unit tests for getting remote files

This tests the current behaviour of the
xfunc_scp_compgen_remote_files function, including escaping, by
introducing a fixture to mock ssh invocation on the local host.

test/fixtures/scp/bin/ssh

@@ -0,0 +1,10 @@
+#!/bin/sh
+for arg in "$@"; do
+    case "$arg" in
+	-o)
+		shift 2;;
+	local)
+		shift 1;;
+    esac
+done
+$@

test/t/test_scp.py

@@ -2,11 +2,12 @@
 
 import pytest
 
-from conftest import assert_bash_exec
+from conftest import assert_bash_exec, bash_env_saved
 
 LIVE_HOST = "bash_completion"
 
 
+@pytest.mark.bashcomp(ignore_env=r"^\+COMPREPLY=")
 class TestScp:
     @pytest.mark.complete("scp -F config ", cwd="scp")
     def test_basic(self, hosts, completion):
@@ -23,7 +24,7 @@ def test_basic(self, hosts, completion):
                     )
                 ),
                 # Local filenames
-                ["config", "known_hosts", r"spaced\ \ conf"],
+                ["bin/", "config", "known_hosts", r"spaced\ \ conf"],
             )
         )
         assert completion == expected
@@ -43,7 +44,7 @@ def test_basic_spaced_conf(self, hosts, completion):
                     )
                 ),
                 # Local filenames
-                ["config", "known_hosts", r"spaced\ \ conf"],
+                ["bin/", "config", "known_hosts", r"spaced\ \ conf"],
             )
         )
         assert completion == expected
@@ -95,3 +96,32 @@ def test_remote_path_with_nullglob(self, completion):
     )
     def test_remote_path_with_failglob(self, completion):
         assert not completion
+
+    @pytest.fixture(scope="class")
+    def ssh_mock(self, request, bash):
+        with bash_env_saved(bash) as bash_env:
+            bash_env.write_variable(
+                "PATH",
+                "$PWD/scp/bin:$PATH",
+                quote=False,
+            )
+            yield
+
+    def test_xfunc_remote_files(self, bash, ssh_mock):
+        with bash_env_saved(bash) as bash_env:
+            bash_env.write_variable("cur", "local:shared/default/")
+            completions = (
+                assert_bash_exec(
+                    bash,
+                    r'_comp_compgen -ax scp remote_files; printf "%s\n" "${COMPREPLY[@]}";',
+                    want_output=True,
+                )
+                .strip()
+                .splitlines()
+            )
+        assert completions == [
+            "shared/default/bar ",
+            r"shared/default/bar\\\ bar.d/",
+            "shared/default/foo ",
+            "shared/default/foo.d/",
+        ]