Add experimental _to_json and _from_json to TestReport and CollectReport

This methods were moved from xdist (ca03269).

Our intention is to keep this code closer to the core, given that it
might break easily due to refactorings.

Having it in the core might also allow to improve the code by moving
some responsibility to the "code" objects (ReprEntry, etc) which
are often found in the reports.

Finally pytest-xdist and pytest-subtests can use those functions
instead of coding it themselves.

testing/test_reports.py

@@ -0,0 +1,183 @@
+from _pytest.reports import CollectReport
+from _pytest.reports import TestReport
+
+
+class TestReportSerialization(object):
+    """
+    All the tests in this class came originally from test_remote.py in xdist (ca03269).
+    """
+
+    def test_xdist_longrepr_to_str_issue_241(self, testdir):
+        testdir.makepyfile(
+            """
+            import os
+            def test_a(): assert False
+            def test_b(): pass
+        """
+        )
+        reprec = testdir.inline_run()
+        reports = reprec.getreports("pytest_runtest_logreport")
+        assert len(reports) == 6
+        test_a_call = reports[1]
+        assert test_a_call.when == "call"
+        assert test_a_call.outcome == "failed"
+        assert test_a_call._to_json()["longrepr"]["reprtraceback"]["style"] == "long"
+        test_b_call = reports[4]
+        assert test_b_call.when == "call"
+        assert test_b_call.outcome == "passed"
+        assert test_b_call._to_json()["longrepr"] is None
+
+    def test_xdist_report_longrepr_reprcrash_130(self, testdir):
+        reprec = testdir.inline_runsource(
+            """
+                    import py
+                    def test_fail(): assert False, 'Expected Message'
+                """
+        )
+        reports = reprec.getreports("pytest_runtest_logreport")
+        assert len(reports) == 3
+        rep = reports[1]
+        added_section = ("Failure Metadata", str("metadata metadata"), "*")
+        rep.longrepr.sections.append(added_section)
+        d = rep._to_json()
+        a = TestReport._from_json(d)
+        # Check assembled == rep
+        assert a.__dict__.keys() == rep.__dict__.keys()
+        for key in rep.__dict__.keys():
+            if key != "longrepr":
+                assert getattr(a, key) == getattr(rep, key)
+        assert rep.longrepr.reprcrash.lineno == a.longrepr.reprcrash.lineno
+        assert rep.longrepr.reprcrash.message == a.longrepr.reprcrash.message
+        assert rep.longrepr.reprcrash.path == a.longrepr.reprcrash.path
+        assert rep.longrepr.reprtraceback.entrysep == a.longrepr.reprtraceback.entrysep
+        assert (
+            rep.longrepr.reprtraceback.extraline == a.longrepr.reprtraceback.extraline
+        )
+        assert rep.longrepr.reprtraceback.style == a.longrepr.reprtraceback.style
+        assert rep.longrepr.sections == a.longrepr.sections
+        # Missing section attribute PR171
+        assert added_section in a.longrepr.sections
+
+    def test_reprentries_serialization_170(self, testdir):
+        from _pytest._code.code import ReprEntry
+
+        reprec = testdir.inline_runsource(
+            """
+                            def test_repr_entry():
+                                x = 0
+                                assert x
+                        """,
+            "--showlocals",
+        )
+        reports = reprec.getreports("pytest_runtest_logreport")
+        assert len(reports) == 3
+        rep = reports[1]
+        d = rep._to_json()
+        a = TestReport._from_json(d)
+
+        rep_entries = rep.longrepr.reprtraceback.reprentries
+        a_entries = a.longrepr.reprtraceback.reprentries
+        for i in range(len(a_entries)):
+            assert isinstance(rep_entries[i], ReprEntry)
+            assert rep_entries[i].lines == a_entries[i].lines
+            assert rep_entries[i].reprfileloc.lineno == a_entries[i].reprfileloc.lineno
+            assert (
+                rep_entries[i].reprfileloc.message == a_entries[i].reprfileloc.message
+            )
+            assert rep_entries[i].reprfileloc.path == a_entries[i].reprfileloc.path
+            assert rep_entries[i].reprfuncargs.args == a_entries[i].reprfuncargs.args
+            assert rep_entries[i].reprlocals.lines == a_entries[i].reprlocals.lines
+            assert rep_entries[i].style == a_entries[i].style
+
+    def test_reprentries_serialization_196(self, testdir):
+        from _pytest._code.code import ReprEntryNative
+
+        reprec = testdir.inline_runsource(
+            """
+                            def test_repr_entry_native():
+                                x = 0
+                                assert x
+                        """,
+            "--tb=native",
+        )
+        reports = reprec.getreports("pytest_runtest_logreport")
+        assert len(reports) == 3
+        rep = reports[1]
+        d = rep._to_json()
+        a = TestReport._from_json(d)
+
+        rep_entries = rep.longrepr.reprtraceback.reprentries
+        a_entries = a.longrepr.reprtraceback.reprentries
+        for i in range(len(a_entries)):
+            assert isinstance(rep_entries[i], ReprEntryNative)
+            assert rep_entries[i].lines == a_entries[i].lines
+
+    def test_itemreport_outcomes(self, testdir):
+        reprec = testdir.inline_runsource(
+            """
+            import py
+            def test_pass(): pass
+            def test_fail(): 0/0
+            @py.test.mark.skipif("True")
+            def test_skip(): pass
+            def test_skip_imperative():
+                py.test.skip("hello")
+            @py.test.mark.xfail("True")
+            def test_xfail(): 0/0
+            def test_xfail_imperative():
+                py.test.xfail("hello")
+        """
+        )
+        reports = reprec.getreports("pytest_runtest_logreport")
+        assert len(reports) == 17  # with setup/teardown "passed" reports
+        for rep in reports:
+            d = rep._to_json()
+            newrep = TestReport._from_json(d)
+            assert newrep.passed == rep.passed
+            assert newrep.failed == rep.failed
+            assert newrep.skipped == rep.skipped
+            if newrep.skipped and not hasattr(newrep, "wasxfail"):
+                assert len(newrep.longrepr) == 3
+            assert newrep.outcome == rep.outcome
+            assert newrep.when == rep.when
+            assert newrep.keywords == rep.keywords
+            if rep.failed:
+                assert newrep.longreprtext == rep.longreprtext
+
+    def test_collectreport_passed(self, testdir):
+        reprec = testdir.inline_runsource("def test_func(): pass")
+        reports = reprec.getreports("pytest_collectreport")
+        for rep in reports:
+            d = rep._to_json()
+            newrep = CollectReport._from_json(d)
+            assert newrep.passed == rep.passed
+            assert newrep.failed == rep.failed
+            assert newrep.skipped == rep.skipped
+
+    def test_collectreport_fail(self, testdir):
+        reprec = testdir.inline_runsource("qwe abc")
+        reports = reprec.getreports("pytest_collectreport")
+        assert reports
+        for rep in reports:
+            d = rep._to_json()
+            newrep = CollectReport._from_json(d)
+            assert newrep.passed == rep.passed
+            assert newrep.failed == rep.failed
+            assert newrep.skipped == rep.skipped
+            if rep.failed:
+                assert newrep.longrepr == str(rep.longrepr)
+
+    def test_extended_report_deserialization(self, testdir):
+        reprec = testdir.inline_runsource("qwe abc")
+        reports = reprec.getreports("pytest_collectreport")
+        assert reports
+        for rep in reports:
+            rep.extra = True
+            d = rep._to_json()
+            newrep = CollectReport._from_json(d)
+            assert newrep.extra
+            assert newrep.passed == rep.passed
+            assert newrep.failed == rep.failed
+            assert newrep.skipped == rep.skipped
+            if rep.failed:
+                assert newrep.longrepr == str(rep.longrepr)