SCM: allow multiple DVC repos inside single SCM repo (#3257)

tests/func/test_init.py

@@ -1,5 +1,8 @@
+import logging
 import os
 
+from dvc.compat import fspath
+from dvc.config import Config
 from dvc.exceptions import InitError
 from dvc.main import main
 from dvc.repo import Repo as DvcRepo
@@ -49,21 +52,20 @@ class TestInitNoSCMFail(TestDir):
         self.assertNotEqual(ret, 0)
 
 
-class TestInitNoSCM(TestDir):
-    def _test_init(self):
-        self.assertTrue(os.path.exists(DvcRepo.DVC_DIR))
-        self.assertTrue(os.path.isdir(DvcRepo.DVC_DIR))
+def test_init_no_scm_api(tmp_dir):
+    repo = DvcRepo.init(no_scm=True)
 
-    def test_api(self):
-        DvcRepo.init(no_scm=True)
+    assert (tmp_dir / DvcRepo.DVC_DIR).is_dir()
+    assert repo.config["core"]["no_scm"]
 
-        self._test_init()
 
-    def test_cli(self):
-        ret = main(["init", "--no-scm"])
-        self.assertEqual(ret, 0)
+def test_init_no_scm_cli(tmp_dir):
+    ret = main(["init", "--no-scm"])
+    assert ret == 0
 
-        self._test_init()
+    dvc_path = tmp_dir / DvcRepo.DVC_DIR
+    assert dvc_path.is_dir()
+    assert Config(fspath(dvc_path))["core"]["no_scm"]
 
 
 def test_init_quiet_should_not_display_welcome_screen(tmp_dir, scm, caplog):
@@ -71,3 +73,32 @@ def test_init_quiet_should_not_display_welcome_screen(tmp_dir, scm, caplog):
 
     assert 0 == ret
     assert "" == caplog.text
+
+
+def test_allow_init_dvc_subdir(tmp_dir, scm, monkeypatch):
+    tmp_dir.gen({"subdir": {}})
+
+    with monkeypatch.context() as m:
+        m.chdir("subdir")
+        assert main(["init", "--subdir"]) == 0
+
+    repo = DvcRepo("subdir")
+    assert repo.root_dir == fspath(tmp_dir / "subdir")
+    assert repo.scm.root_dir == fspath(tmp_dir)
+
+
+def test_subdir_init_no_option(tmp_dir, scm, monkeypatch, caplog):
+    tmp_dir.gen({"subdir": {}})
+
+    caplog.clear()
+    with monkeypatch.context() as m:
+        m.chdir("subdir")
+        with caplog.at_level(logging.ERROR, logger="dvc"):
+            assert main(["init"]) == 1
+
+    assert (
+        "{} is not tracked by any supported SCM tool (e.g. Git). "
+        "Use `--no-scm` if you don't want to use any SCM or "
+        "`--subdir` if initializing inside a subdirectory of a parent SCM "
+        "repository.".format(fspath(tmp_dir / "subdir"))
+    ) in caplog.text