add: optimistic_updates config to prioritize updates over status chec…

…ks (#64)

instead of waiting for status checks to finish before updating we will update the branch.

README.md

@@ -75,6 +75,7 @@ Kodiak won't merge PRs if branch protection is disabled.
    delete_branch_on_merge = true # default: false
    block_on_reviews_requested = false # default: false
    notify_on_conflict = true # default: true
+   optimistic_updates = true # default: true
 
    [merge.message]
    title = "pull_request_title" # default: "github_default"

kodiak/config.py

@@ -57,6 +57,8 @@ class Merge(BaseModel):
     block_on_reviews_requested: bool = False
     # comment on merge conflict and remove automerge label
     notify_on_conflict: bool = True
+    # don't wait for status checks to run before updating branch
+    optimistic_updates: bool = True
     # configuration for commit message of merge
     message: MergeMessage = MergeMessage()
 

kodiak/evaluation.py

@@ -204,6 +204,11 @@ def mergeable(
             if successful_reviews < branch_protection.requiredApprovingReviewCount:
                 raise NotQueueable("missing required review count")
 
+        if branch_protection.requiresCommitSignatures and not valid_signature:
+            raise NotQueueable("missing required signature")
+
+        required: typing.Set[str] = set()
+        passing: typing.Set[str] = set()
         if branch_protection.requiresStatusChecks:
             failing_contexts: typing.List[str] = []
             pending_contexts: typing.List[str] = []
@@ -241,17 +246,29 @@ def mergeable(
                 # is a similar question for the review counting.
                 raise NotQueueable("failing required status checks")
             passing = set(passing_contexts)
-            if len(required - passing) > 0:
-                raise WaitingForChecks("missing required status checks")
 
-        if branch_protection.requiresCommitSignatures:
-            if not valid_signature:
-                raise NotQueueable("missing required signature")
-        if (
+        need_branch_update = (
             branch_protection.requiresStrictStatusChecks
             and pull_request.mergeStateStatus == MergeStateStatus.BEHIND
-        ):
-            raise NeedsBranchUpdate("behind branch. need update")
+        )
+        wait_for_checks = (
+            branch_protection.requiresStatusChecks and len(required - passing) > 0
+        )
+
+        # prioritize branch updates over waiting for status checks to complete
+        if config.merge.optimistic_updates:
+            if need_branch_update:
+                raise NeedsBranchUpdate("behind branch. need update")
+            if wait_for_checks:
+                raise WaitingForChecks("missing required status checks")
+        # almost the same as the pervious case, but we prioritize status checks
+        # over branch updates.
+        else:
+            if wait_for_checks:
+                raise WaitingForChecks("missing required status checks")
+            if need_branch_update:
+                raise NeedsBranchUpdate("behind branch. need update")
+
         raise NotQueueable("Could not determine why PR is blocked")
 
     # okay to merge

kodiak/test/fixtures/config/v1-default.toml

@@ -9,6 +9,7 @@ method = "merge"
 delete_branch_on_merge = false
 block_on_reviews_requested = false
 notify_on_conflict = true
+optimistic_updates = true
 
 [merge.message]
 title = "github_default"

kodiak/test/fixtures/config/v1-opposite.toml

@@ -10,6 +10,7 @@ method = "squash" # default: "merge"
 delete_branch_on_merge = true # default: False
 block_on_reviews_requested = true # default: false
 notify_on_conflict = false # default: true
+optimistic_updates = false # default: true
 
 [merge.message]
 title = "pull_request_title" # default: "github_default"

kodiak/test_config.py

@@ -48,6 +48,7 @@ def test_config_parsing_opposite() -> None:
             delete_branch_on_merge=True,
             block_on_reviews_requested=True,
             notify_on_conflict=False,
+            optimistic_updates=False,
             message=MergeMessage(
                 title=MergeTitleStyle.pull_request_title,
                 body=MergeBodyStyle.pull_request_body,

kodiak/test_evaluation.py

@@ -1,4 +1,5 @@
 from datetime import datetime, timedelta
+from typing import List
 
 import pytest
 
@@ -817,3 +818,51 @@ def test_app_id(
             valid_signature=False,
             valid_merge_methods=[],
         )
+
+
+def test_config_merge_optimistic_updates(
+    pull_request: PullRequest, config: V1, branch_protection: BranchProtectionRule
+) -> None:
+    """
+    If optimisitc_updates are enabled, branch updates should be prioritized over
+    waiting for running status checks to complete.
+
+    Otherwise, status checks should be checked before updating.
+    """
+    branch_protection.requiredApprovingReviewCount = 0
+
+    branch_protection.requiresStrictStatusChecks = True
+    pull_request.mergeStateStatus = MergeStateStatus.BEHIND
+
+    branch_protection.requiresStatusChecks = True
+    branch_protection.requiredStatusCheckContexts = ["ci/lint", "ci/test"]
+    contexts: List[StatusContext] = []
+
+    config.merge.optimistic_updates = True
+    with pytest.raises(NeedsBranchUpdate):
+        mergeable(
+            app_id="1234",
+            config=config,
+            pull_request=pull_request,
+            branch_protection=branch_protection,
+            review_requests_count=0,
+            reviews=[],
+            contexts=contexts,
+            check_runs=[],
+            valid_signature=False,
+            valid_merge_methods=[MergeMethod.squash],
+        )
+    config.merge.optimistic_updates = False
+    with pytest.raises(WaitingForChecks):
+        mergeable(
+            app_id="1234",
+            config=config,
+            pull_request=pull_request,
+            branch_protection=branch_protection,
+            review_requests_count=0,
+            reviews=[],
+            contexts=contexts,
+            check_runs=[],
+            valid_signature=False,
+            valid_merge_methods=[MergeMethod.squash],
+        )