spec: support exists() on directories pre-cache

CHANGELOG.md

@@ -1,4 +1,8 @@
 **Change Log**
+v0.7.5
+------
+- `exists()` calls now also checks whether a directory with that name exists or not. Previously this was only checked from the cache.
+
 v0.7.4
 ------
 - Added the location_mode parameter to AzureBlobFileSystem object, and set default to "primary" to enable Access Control Lists and RA-GRS access.  Valid values are "primary" and "secondary"

adlfs/spec.py

@@ -1292,8 +1292,19 @@ async def _exists(self, path):
                 return True
 
         async with self.service_client.get_blob_client(container_name, path) as bc:
-            exists = await bc.exists()
-        return exists
+            if await bc.exists():
+                return True
+
+        dir_path = path.rstrip("/") + "/"
+        async with self.service_client.get_container_client(
+            container=container_name
+        ) as container_client:
+            async for blob in container_client.list_blobs(
+                results_per_page=1, name_starts_with=dir_path
+            ):
+                return True
+            else:
+                return False
 
     async def _pipe_file(self, path, value, overwrite=True, **kwargs):
         """Set the bytes of given file"""

adlfs/tests/test_spec.py

@@ -1244,11 +1244,28 @@ def test_exists(storage):
     assert not fs.exists("data/not-a-key")
 
 
-def test_find_with_prefix(storage):
+def test_exists_directory(storage):
     fs = AzureBlobFileSystem(
         account_name=storage.account_name, connection_string=CONN_STR
     )
 
+    fs.mkdir("temp_exists")
+    fs.touch("temp_exists/data/data.txt")
+    fs.touch("temp_exists/data/something/data.txt")
+    fs.invalidate_cache()
+
+    assert fs.exists("temp_exists/data/something/")
+    assert fs.exists("temp_exists/data/something")
+    assert fs.exists("temp_exists/data/")
+    assert fs.exists("temp_exists/data")
+    assert fs.exists("temp_exists/")
+    assert fs.exists("temp_exists")
+
+
+def test_find_with_prefix(storage):
+    fs = AzureBlobFileSystem(
+        account_name=storage.account_name, connection_string=CONN_STR
+    )
     test_bucket_name = "data"
 
     for cursor in range(25):