Add draft status to signals

README.md

@@ -118,19 +118,23 @@ merge:
     # Pull requests with auto merge enabled are added to the trigger.
     auto_merge: true
 
+    # Pull requests in draft status are added to the trigger.
+    draft: true
+
   # "ignore" defines the set of pull request ignored by bulldozer. If the
   # section is missing, bulldozer considers all pull requests. It takes the
   # same keys as the "trigger" section.
   ignore:
     labels: ["do not merge"]
     comment_substrings: ["==DO_NOT_MERGE=="]
+    draft: true
 
   # "method" defines the merge method. The available options are "merge",
   # "rebase", "squash", and "ff-only".
   method: squash
 
   ##### branch_method has been DEPRECATED in favor of merge_method #####
-  # 
+  #
   # Allows the merge method that is used when auto-merging a PR to be different
   # target branch. The keys of the hash are the target branch name, and the values are the merge method that
   # will be used for PRs targeting that branch. The valid values are the same as for the "method" key.
@@ -142,9 +146,9 @@ merge:
 
   # Allows the merge method that is used when auto-merging a PR to be different
   # based on trigger criteria. The first method where ALL triggers match will
-  # be used. Otherwise, the method specified previously in "merge.method" will 
+  # be used. Otherwise, the method specified previously in "merge.method" will
   # be used.
-  # - ALL trigger criteria must match, unlike merge/trigger where ANY match 
+  # - ALL trigger criteria must match, unlike merge/trigger where ANY match
   # will trigger bulldozer.
   # - This will override any branch_method logic if one of the methods is
   # triggered
@@ -428,7 +432,7 @@ previously installed.
 
 ### Reducing Update Commit and CI Pressure
 
-The Bulldozer "Update" feature is useful when keeping branches up-to-date,  but 
+The Bulldozer "Update" feature is useful when keeping branches up-to-date,  but
 can cause lots of pressure on CI build systems and Github when there are many pull requests
 open on a single repository.
 

bulldozer/signals.go

@@ -41,6 +41,7 @@ type BranchesSignal []string
 type BranchPatternsSignal []string
 type MaxCommitsSignal int
 type AutoMergeSignal bool
+type DraftSignal bool
 
 type Signals struct {
 	Labels            LabelsSignal            `yaml:"labels"`
@@ -51,6 +52,7 @@ type Signals struct {
 	BranchPatterns    BranchPatternsSignal    `yaml:"branch_patterns"`
 	MaxCommits        MaxCommitsSignal        `yaml:"max_commits"`
 	AutoMerge         AutoMergeSignal         `yaml:"auto_merge"`
+	Draft             DraftSignal             `yaml:"draft"`
 }
 
 func (signal LabelsSignal) Enabled() bool {
@@ -85,6 +87,10 @@ func (signal AutoMergeSignal) Enabled() bool {
 	return bool(signal)
 }
 
+func (signal DraftSignal) Enabled() bool {
+	return bool(signal)
+}
+
 func (s Signals) Enabled() bool {
 	return s.Labels.Enabled() ||
 		s.CommentSubstrings.Enabled() ||
@@ -149,6 +155,7 @@ func (s Signals) MatchesAny(ctx context.Context, pullCtx pull.Context, tag strin
 		&s.Branches,
 		&s.BranchPatterns,
 		&s.AutoMerge,
+		&s.Draft,
 	}
 
 	for _, signal := range signals {
@@ -366,3 +373,20 @@ func (signal AutoMergeSignal) Matches(ctx context.Context, pullCtx pull.Context,
 
 	return false, "", nil
 }
+
+func (signal DraftSignal) Matches(ctx context.Context, pullCtx pull.Context, tag string) (bool, string, error) {
+	logger := zerolog.Ctx(ctx)
+
+	if !signal.Enabled() {
+		logger.Debug().Msgf("No valid draft pr value has been provided to match against")
+		return false, "", nil
+	}
+
+	isDraft := pullCtx.IsDraft(ctx)
+
+	if isDraft {
+		return true, "pull request is a draft", nil
+	}
+
+	return false, "", nil
+}

bulldozer/signals_test.go

@@ -33,6 +33,7 @@ func TestSignalsMatchesAny(t *testing.T) {
 		Branches:          []string{"develop"},
 		BranchPatterns:    []string{"test/.*", "^feature/.*$"},
 		AutoMerge:         true,
+		Draft:             true,
 	}
 
 	ctx := context.Background()
@@ -141,6 +142,13 @@ func TestSignalsMatchesAny(t *testing.T) {
 			Matches: true,
 			Reason:  "pull request is configured to auto merge",
 		},
+		"draftMatch": {
+			PullContext: &pulltest.MockPullContext{
+				IsDraftValue: true,
+			},
+			Matches: true,
+			Reason:  "pull request is a draft",
+		},
 	}
 
 	for name, test := range tests {
@@ -272,6 +280,7 @@ func TestSignalsMatchesAll(t *testing.T) {
 		BranchPatterns:    []string{"test/.*", "^feature/.*$"},
 		MaxCommits:        2,
 		AutoMerge:         true,
+		Draft:             true,
 	}
 
 	ctx := context.Background()
@@ -292,6 +301,7 @@ func TestSignalsMatchesAll(t *testing.T) {
 					{SHA: "2", Message: "commit 2"},
 				},
 				AutoMergeValue: true,
+				IsDraftValue:   true,
 			},
 			Matches: true,
 			Reason:  `pull request matches all testlist signals`,