condition can be evaluated in the real time

README.rst

@@ -108,6 +108,20 @@ You can also specify an optional ``condition`` in the re-run marker:
       import random
       assert random.choice([True, False])
 
+You can use ``@pytest.mark.flaky(condition)`` similarly as ``@pytest.mark.skipif(condition)``, see `pytest-mark-skipif <https://docs.pytest.org/en/6.2.x/reference.html#pytest-mark-skipif>`_
+
+.. code-block:: python
+
+    @pytest.mark.flaky(reruns=2,condition="sys.platform.startswith('win32')")
+    def test_example():
+        import random
+        assert random.choice([True, False])
+    # totally same as the above
+    @pytest.mark.flaky(reruns=2,condition=sys.platform.startswith("win32"))
+    def test_example():
+      import random
+      assert random.choice([True, False])
+
 Note that the test will re-run for any ``condition`` that is truthy.
 
 Output

pytest_rerunfailures.py

@@ -1,9 +1,14 @@
+import os
+import platform
 import re
+import sys
 import time
+import traceback
 import warnings
 
 import pkg_resources
 import pytest
+from _pytest.outcomes import fail
 from _pytest.runner import runtestprotocol
 
 HAS_RESULTLOG = False
@@ -184,11 +189,61 @@ def get_reruns_condition(item):
 
     condition = True
     if rerun_marker is not None and "condition" in rerun_marker.kwargs:
-        condition = rerun_marker.kwargs["condition"]
+        condition = evaluate_condition(
+            item, rerun_marker, rerun_marker.kwargs["condition"]
+        )
 
     return condition
 
 
+def evaluate_condition(item, mark, condition: object) -> bool:
+    """
+    copy from python3.8 _pytest.skipping.py
+    """
+    result = False
+    # String condition.
+    if isinstance(condition, str):
+        globals_ = {
+            "os": os,
+            "sys": sys,
+            "platform": platform,
+            "config": item.config,
+        }
+        if hasattr(item, "obj"):
+            globals_.update(item.obj.__globals__)  # type: ignore[attr-defined]
+        try:
+            filename = f"<{mark.name} condition>"
+            condition_code = compile(condition, filename, "eval")
+            result = eval(condition_code, globals_)
+        except SyntaxError as exc:
+            msglines = [
+                "Error evaluating %r condition" % mark.name,
+                "    " + condition,
+                "    " + " " * (exc.offset or 0) + "^",
+                "SyntaxError: invalid syntax",
+            ]
+            fail("\n".join(msglines), pytrace=False)
+        except Exception as exc:
+            msglines = [
+                "Error evaluating %r condition" % mark.name,
+                "    " + condition,
+                *traceback.format_exception_only(type(exc), exc),
+            ]
+            fail("\n".join(msglines), pytrace=False)
+
+    # Boolean condition.
+    else:
+        try:
+            result = bool(condition)
+        except Exception as exc:
+            msglines = [
+                "Error evaluating %r condition as a boolean" % mark.name,
+                *traceback.format_exception_only(type(exc), exc),
+            ]
+            fail("\n".join(msglines), pytrace=False)
+    return result
+
+
 def _remove_cached_results_from_failed_fixtures(item):
     """
     Note: remove all cached_result attribute from every fixture

test_pytest_rerunfailures.py

@@ -529,8 +529,6 @@ def test_only_rerun_flag(testdir, only_rerun_texts, should_rerun):
         (False, 0),
         (1, 2),
         (0, 0),
-        ("'non-empty'", 2),
-        ("''", 0),
         (["list"], 2),
         ([], 0),
         ({"dict": 1}, 2),
@@ -550,3 +548,37 @@ def test_fail_two():
 
     result = testdir.runpytest()
     assert_outcomes(result, passed=0, failed=1, rerun=expected_reruns)
+
+
+@pytest.mark.parametrize(
+    "condition, expected_reruns",
+    [('sys.platform.startswith("non-exists") == False', 2), ("os.getpid() != -1", 2)],
+)
+# before evaluating the condition expression, sys&os&platform package has been imported
+def test_reruns_with_string_condition(testdir, condition, expected_reruns):
+    testdir.makepyfile(
+        f"""
+           import pytest
+
+           @pytest.mark.flaky(reruns=2, condition='{condition}')
+           def test_fail_two():
+               assert False"""
+    )
+    result = testdir.runpytest()
+    assert_outcomes(result, passed=0, failed=1, rerun=2)
+
+
+def test_reruns_with_string_condition_with_global_var(testdir):
+    testdir.makepyfile(
+        """
+              import pytest
+
+              rerunBool = False
+              @pytest.mark.flaky(reruns=2, condition='rerunBool')
+              def test_fail_two():
+                  global rerunBool
+                  rerunBool = True
+                  assert False"""
+    )
+    result = testdir.runpytest()
+    assert_outcomes(result, passed=0, failed=1, rerun=2)