PyTest.summaryf: always report count of failures and errors

summaryf needs to always return the count of failures, errors, skips
for two reasons:

 - nxdtest sets error_count += 1 when the test program's returncode is
not zero, so if we don't set error_count explicitly, the number of
errors will be 1 when there are only failures
 - without error_count / failure_count, _test_result_summary does not
display the global test result as pass or fail but as ?

/reviewed-by @kirr
/reviewed-on nexedi/nxdtest!17

nxdtest/__init__.py

@@ -513,9 +513,7 @@ class PyTest:
 
         stat = {'test_count': 0}
         def stat_set(stat_key, from_name):
-            v = get(from_name)
-            if v is None:
-                return
+            v = get(from_name, 0)
             stat[stat_key] = v
             stat['test_count'] += v
         stat_set('skip_count', 'skipped')

nxdtest/nxdtest_pytest_test.py

@@ -27,6 +27,20 @@ from golang import b
 testv = []
 def case1(name, out, err, summaryok): testv.append((name, out, err, summaryok))
 
+case1('ok', b("""\
+============================== test session starts ===============================
+platform linux -- Python 3.7.7, pytest-4.6.11, py-1.9.0, pluggy-0.13.1
+rootdir: /srv/slapgrid/slappart15/srv/runner/software/104d3d67a7dca200da22b97280c85eb6/parts/nxdtest, inifile: pytest.ini
+plugins: timeout-1.4.2, mock-2.0.0
+collected 1 item
+
+test.py .                                                                  [100%]
+
+============================ 1 passed in 0.01 seconds ============================
+"""),
+b(''),
+'ok\ttestname\t1.000s\t# 1t 0e 0f 0s')
+
 case1('ok+xfail', b("""\
 ============================= test session starts ==============================
 platform linux2 -- Python 2.7.18, pytest-4.6.11, py-1.9.0, pluggy-0.13.1
@@ -42,7 +56,7 @@ zodbtools/test/test_zodb.py ........                                     [100%]
 =============== 41 passed, 2 xfailed, 1 warnings in 4.62 seconds ===============
 """),
 b(''),
-'?\ttestname\t1.000s\t# 43t ?e ?f ?s')
+'ok\ttestname\t1.000s\t# 43t 0e 0f 0s')
 
 case1('ok+fail', b("""\
 ============================= test session starts ==============================
@@ -115,7 +129,7 @@ golang/time_test.py:106: AssertionError
 =============== 1 failed, 98 passed, 13 skipped in 26.85 seconds ===============
 """),
 b(''),
-'?\ttestname\t1.000s\t# 112t ?e 1f 13s')
+'fail\ttestname\t1.000s\t# 112t 0e 1f 13s')
 
 case1('ok+tailtext', b("""\
 date:   Sun, 08 Nov 2020 12:26:24 MSK
@@ -134,7 +148,7 @@ wcfs: 2020/11/08 12:26:38 /tmp/testdb_fs.B3rbby/1.fs: watcher: stat /tmp/testdb_
 # unmount/stop wcfs pid39595 @ /tmp/wcfs/d0b5d036a2cce47fe73003cf2d9f0b22c7043817
 """),
 b(''),
-'?\ttestname\t1.000s\t# 55t ?e ?f ?s')
+'ok\ttestname\t1.000s\t# 55t 0e 0f 0s')
 
 
 @pytest.mark.parametrize("name,out,err,summaryok", testv)