Function for claiming multiple resources at once.

Like claim_for_update, the claim_many_for_update claims resources with
an expiring lock. This was written to allow the updating of multiple
application roles with a single cloud_id, since multiple application
roles will map to a single Azure Active Directory user.

tests/models/test_utils.py

@@ -0,0 +1,104 @@
+from threading import Thread
+
+from atst.domain.exceptions import ClaimFailedException
+from atst.models.utils import claim_for_update, claim_many_for_update
+
+from tests.factories import EnvironmentFactory
+
+
+def test_claim_for_update(session):
+    environment = EnvironmentFactory.create()
+
+    satisfied_claims = []
+    exceptions = []
+
+    # Two threads race to do work on environment and check out the lock
+    class FirstThread(Thread):
+        def run(self):
+            try:
+                with claim_for_update(environment) as env:
+                    assert env.claimed_until
+                    satisfied_claims.append("FirstThread")
+            except ClaimFailedException:
+                exceptions.append("FirstThread")
+
+    class SecondThread(Thread):
+        def run(self):
+            try:
+                with claim_for_update(environment) as env:
+                    assert env.claimed_until
+                    satisfied_claims.append("SecondThread")
+            except ClaimFailedException:
+                exceptions.append("SecondThread")
+
+    t1 = FirstThread()
+    t2 = SecondThread()
+    t1.start()
+    t2.start()
+    t1.join()
+    t2.join()
+
+    session.refresh(environment)
+
+    assert len(satisfied_claims) == 1
+    assert len(exceptions) == 1
+
+    if satisfied_claims == ["FirstThread"]:
+        assert exceptions == ["SecondThread"]
+    else:
+        assert satisfied_claims == ["SecondThread"]
+        assert exceptions == ["FirstThread"]
+
+    # The claim is released
+    assert environment.claimed_until is None
+
+
+def test_claim_many_for_update(session):
+    environments = [
+        EnvironmentFactory.create(),
+        EnvironmentFactory.create(),
+    ]
+
+    satisfied_claims = []
+    exceptions = []
+
+    # Two threads race to do work on environment and check out the lock
+    class FirstThread(Thread):
+        def run(self):
+            try:
+                with claim_many_for_update(environments) as envs:
+                    assert all([e.claimed_until for e in envs])
+                    satisfied_claims.append("FirstThread")
+            except ClaimFailedException:
+                exceptions.append("FirstThread")
+
+    class SecondThread(Thread):
+        def run(self):
+            try:
+                with claim_many_for_update(environments) as envs:
+                    assert all([e.claimed_until for e in envs])
+                    satisfied_claims.append("SecondThread")
+            except ClaimFailedException:
+                exceptions.append("SecondThread")
+
+    t1 = FirstThread()
+    t2 = SecondThread()
+    t1.start()
+    t2.start()
+    t1.join()
+    t2.join()
+
+    for env in environments:
+        session.refresh(env)
+
+    assert len(satisfied_claims) == 1
+    assert len(exceptions) == 1
+
+    if satisfied_claims == ["FirstThread"]:
+        assert exceptions == ["SecondThread"]
+    else:
+        assert satisfied_claims == ["SecondThread"]
+        assert exceptions == ["FirstThread"]
+
+    # The claim is released
+    # assert environment.claimed_until is None