Increase required verbosity level for debug output

To show the subclassed file in legacy test suits in the runtest output
you have to set the verbosity level to at least "-vv" now.

Closes #3211

Author: twmr

changelog/4159.feature.rst

@@ -0,0 +1,3 @@
+For test-suites containing test classes, the information about the subclassed
+module is now output only if a higher verbosity level is specified (at least
+"-vv").

src/_pytest/terminal.py

@@ -676,7 +676,9 @@ def mkrel(nodeid):
 
         if fspath:
             res = mkrel(nodeid).replace("::()", "")  # parens-normalization
-            if nodeid.split("::")[0] != fspath.replace("\\", nodes.SEP):
+            if self.verbosity >= 2 and nodeid.split("::")[0] != fspath.replace(
+                "\\", nodes.SEP
+            ):
                 res += " <- " + self.startdir.bestrelpath(fspath)
         else:
             res = "[location]"

testing/test_terminal.py

@@ -154,7 +154,7 @@ class TestMore(BaseTests):
         )
         result = testdir.runpytest(p2)
         result.stdout.fnmatch_lines(["*test_p2.py .*", "*1 passed*"])
-        result = testdir.runpytest("-v", p2)
+        result = testdir.runpytest("-vv", p2)
         result.stdout.fnmatch_lines(
             ["*test_p2.py::TestMore::test_p1* <- *test_p1.py*PASSED*"]
         )
@@ -170,7 +170,7 @@ def test_method(self):
                 """
             )
         )
-        result = testdir.runpytest("-v")
+        result = testdir.runpytest("-vv")
         assert result.ret == 0
         result.stdout.fnmatch_lines(["*a123/test_hello123.py*PASS*"])
         assert " <- " not in result.stdout.str()