ls: support versions (#509)

`find` already supports this useful flag, and this PR is adding the same flag
to `ls`, same as in `s3fs.ls`.

gcsfs/core.py

@@ -815,14 +815,26 @@ async def _glob(self, path, prefix="", **kwargs):
             prefix = path[:ind].split("/")[-1]
         return await super()._glob(path, prefix=prefix, **kwargs)
 
-    async def _ls(self, path, detail=False, prefix="", **kwargs):
+    async def _ls(self, path, detail=False, prefix="", versions=False, **kwargs):
         """List objects under the given '/{bucket}/{prefix} path."""
         path = self._strip_protocol(path).rstrip("/")
 
         if path in ["/", ""]:
             out = await self._list_buckets()
         else:
-            out = await self._list_objects(path, prefix=prefix)
+            out = []
+            for entry in await self._list_objects(
+                path, prefix=prefix, versions=versions
+            ):
+                if versions:
+                    out.append(
+                        {
+                            **entry,
+                            "name": f"{entry['name']}#{entry['generation']}",
+                        }
+                    )
+                else:
+                    out.append(entry)
 
         if detail:
             return out

gcsfs/tests/test_core.py

@@ -1193,6 +1193,22 @@ def test_cp_versioned(gcs_versioned):
     assert gcs_versioned.cat(b) == b"v1"
 
 
+def test_ls_versioned(gcs_versioned):
+    import posixpath
+
+    with gcs_versioned.open(a, "wb") as wo:
+        wo.write(b"v1")
+    v1 = gcs_versioned.info(a)["generation"]
+    with gcs_versioned.open(a, "wb") as wo:
+        wo.write(b"v2")
+    v2 = gcs_versioned.info(a)["generation"]
+    dpath = posixpath.dirname(a)
+    assert {f"{a}#{v1}", f"{a}#{v2}"} == set(gcs_versioned.ls(dpath, versions=True))
+    assert {f"{a}#{v1}", f"{a}#{v2}"} == set(
+        entry["name"] for entry in gcs_versioned.ls(dpath, detail=True, versions=True)
+    )
+
+
 def test_find_versioned(gcs_versioned):
     with gcs_versioned.open(a, "wb") as wo:
         wo.write(b"v1")