config: read merged config by default (#5179)

* config: read merged config by default

* tests: move root test out of config tests

* tests: refactor config tests

* cli: fix cache dir command

tests/func/test_cache.py

@@ -1,5 +1,6 @@
 import os
 import stat
+import textwrap
 
 import configobj
 import pytest
@@ -213,3 +214,27 @@ def test_shared_cache(tmp_dir, dvc, group, dir_mode):
         for fname in fnames:
             path = os.path.join(root, fname)
             assert stat.S_IMODE(os.stat(path).st_mode) == 0o444
+
+
+def test_cache_dir_local(tmp_dir, dvc, caplog):
+    (tmp_dir / ".dvc" / "config.local").write_text(
+        textwrap.dedent(
+            """\
+            [cache]
+                dir = some/path
+            """
+        )
+    )
+    path = os.path.join(dvc.dvc_dir, "some", "path")
+
+    caplog.clear()
+    assert main(["cache", "dir", "--local"]) == 0
+    assert path in caplog.text
+
+    caplog.clear()
+    assert main(["cache", "dir"]) == 0
+    assert path in caplog.text
+
+    caplog.clear()
+    assert main(["cache", "dir", "--repo"]) == 251
+    assert "option 'dir' doesn't exist in section 'cache'" in caplog.text