remote: fix remote default call with no arguments

dvc/command/remote.py

@@ -48,9 +48,13 @@ def run(self):
 
 class CmdRemoteDefault(CmdRemoteConfig):
     def run(self):
-        self.remote_config.set_default(
-            self.args.name, unset=self.args.unset, level=self.args.level
-        )
+        if self.args.name is None and not self.args.unset:
+            name = self.remote_config.get_default(level=self.args.level)
+            print(name)
+        else:
+            self.remote_config.set_default(
+                self.args.name, unset=self.args.unset, level=self.args.level
+            )
         return 0
 
 

dvc/remote/config.py

@@ -151,3 +151,8 @@ def set_default(self, name, unset=False, level=None):
         self.config.set(
             Config.SECTION_CORE, Config.SECTION_CORE_REMOTE, name, level=level
         )
+
+    def get_default(self, level=None):
+        return self.config.get(
+            Config.SECTION_CORE, Config.SECTION_CORE_REMOTE, level=level
+        )

tests/func/test_remote.py

@@ -145,6 +145,13 @@ def test(self):
         self.assertEqual(default, None)
 
 
+def test_show_default(dvc_repo, capsys):
+    assert main(["remote", "default", "foo"]) == 0
+    assert main(["remote", "default"]) == 0
+    out, _ = capsys.readouterr()
+    assert out == "foo\n"
+
+
 class TestRemoteShouldHandleUppercaseRemoteName(TestDvc):
     upper_case_remote_name = "UPPERCASEREMOTE"