Zo doen wijdat in oost

tests/unit/services/nodes/circuit.py

@@ -0,0 +1,97 @@
+# retoor <retoor@molodetz.nl>
+
+from devplacepy.services.nodes.circuit import CLOSED, HALF_OPEN, OPEN, CircuitBreaker
+
+
+class Clock:
+    def __init__(self):
+        self.now = 0.0
+
+    def __call__(self):
+        return self.now
+
+
+def make(failures=3, open_seconds=60):
+    clock = Clock()
+    return CircuitBreaker(failures, open_seconds, clock), clock
+
+
+def test_unknown_keys_are_closed():
+    breaker, _ = make()
+    assert breaker.state("x") == CLOSED and breaker.allows("x")
+
+
+def test_it_opens_at_the_threshold_and_not_before():
+    breaker, _ = make(failures=3)
+    breaker.failure("x")
+    breaker.failure("x")
+    assert breaker.allows("x")
+    breaker.failure("x")
+    assert breaker.state("x") == OPEN and not breaker.allows("x")
+
+
+def test_a_success_resets_the_streak():
+    breaker, _ = make(failures=3)
+    breaker.failure("x")
+    breaker.failure("x")
+    breaker.success("x")
+    breaker.failure("x")
+    breaker.failure("x")
+    assert breaker.allows("x")
+
+
+def test_it_goes_half_open_after_the_cooldown_and_admits_one_probe():
+    breaker, clock = make(failures=1, open_seconds=60)
+    breaker.failure("x")
+    clock.now = 59
+    assert breaker.state("x") == OPEN
+    clock.now = 60
+    assert breaker.state("x") == HALF_OPEN and breaker.allows("x")
+    breaker.begin("x")
+    assert not breaker.allows("x")
+
+
+def test_a_failed_probe_reopens_for_a_full_cooldown():
+    breaker, clock = make(failures=1, open_seconds=60)
+    breaker.failure("x")
+    clock.now = 70
+    breaker.begin("x")
+    breaker.failure("x")
+    assert breaker.state("x") == OPEN
+    clock.now = 129
+    assert breaker.state("x") == OPEN
+    clock.now = 131
+    assert breaker.state("x") == HALF_OPEN
+
+
+def test_a_successful_probe_closes_it():
+    breaker, clock = make(failures=1)
+    breaker.failure("x")
+    clock.now = 100
+    breaker.begin("x")
+    breaker.success("x")
+    assert breaker.state("x") == CLOSED and breaker.allows("x")
+
+
+def test_keys_are_independent():
+    breaker, _ = make(failures=1)
+    breaker.failure(("node", "a"))
+    assert not breaker.allows(("node", "a"))
+    assert breaker.allows(("node", "b"))
+    assert breaker.allows(("destination", "a"))
+
+
+def test_open_count_and_forget():
+    breaker, _ = make(failures=1)
+    breaker.failure("a")
+    breaker.failure("b")
+    assert breaker.open_count() == 2
+    breaker.forget("a")
+    assert breaker.open_count() == 1
+
+
+def test_a_zero_threshold_still_needs_one_failure():
+    breaker = CircuitBreaker(failures=0)
+    assert breaker.allows("x")
+    breaker.failure("x")
+    assert not breaker.allows("x")