Adding Simulation API

README.md

@@ -26,6 +26,7 @@ UI to view the detailed approval status of any pull request.
   - [Approval Policies](#approval-policies)
   - [Disapproval Policy](#disapproval-policy)
   - [Testing and Debugging Policies](#testing-and-debugging-policies)
+    - [Simulation API](#simulation-api)
   - [Caveats and Notes](#caveats-and-notes)
     - [Disapproval is Disabled by Default](#disapproval-is-disabled-by-default)
     - [Interactions with GitHub Reviews](#interactions-with-github-reviews)
@@ -549,6 +550,84 @@ $ rcode=$(curl https://policybot.domain/api/validate -XPUT -T path/to/policy.yml
 $ if [[ "${rcode}" -gt 299 ]]; then cat /tmp/response && exit 1; fi
 ```
 
+#### Simulation API
+
+It can be useful to simulate how Policy Bot would evaluate a pull request if certain conditions were changed. For example: adding a review from a specific user or group, or adjusting the base branch.
+
+An API endpoint exists at `api/simulate/:org/:repo/:prNumber` to simiulate the result of a pull request. Simulations using this endpoint will NOT write the result back to the pull request status check and will instead return the result.
+
+This API requires a GitHub token be passed as a bearer token. The token must have the ability to read the pull request the simulation is being run against.
+
+The API can be used as such:
+
+```sh
+$ curl https://policybot.domain/api/simulate/:org/:repo/:number -H 'authorization: Bearer <token>' -H 'content-type: application/json' -X POST -d '<data>'
+```
+
+Currently the data payload can be configured with a few options:
+
+Ignore any comments from specific users, team members, org members or with specific permissions
+```json
+{
+  "ignore_comments":{
+    "users":["ignored-user"],
+    "teams":["ignored-team"],
+    "organizations":["ignored-org"],
+    "permissions":["admin"]
+  }
+}
+```
+
+Ignore any reviews from specific users, team members, org members or with specific permissions
+```json
+{
+  "ignore_reviews":{
+    "users":["ignored-user"],
+    "teams":["ignored-team"],
+    "organizations":["ignored-org"],
+    "permissions":["admin"]
+  }
+}
+```
+
+Simulate the pull request as if the following comments from the following users had also been added
+```json
+{
+  "add_comments":[
+    {
+      "author":"not-ignored-user",
+      "body":":+1:",
+      "created_at": "2020-11-30T14:20:28.000+07:00",
+      "last_edited_at": "2020-11-30T14:20:28.000+07:00"
+    }
+  ]
+}
+```
+
+Simulate the pull request as if the following reviews from the following users had also been added
+```json
+{
+  "add_reviews":[
+    {
+      "author":"not-ignored-user",
+      "state": "approved",
+      "body": "test approved review",
+      "created_at": "2020-11-30T14:20:28.000+07:00",
+      "last_edited_at": "2020-11-30T14:20:28.000+07:00"
+    }
+  ]
+}
+```
+
+Choose a different base branch when simulating the pull request evaluation
+```json
+{
+  "base_branch": "test-branch"
+}
+```
+
+The above can be combined to form more complex simulations. If a Simulation is run without any data being passed, the pull request is evaluated as is.
+
 ### Caveats and Notes
 
 There are several additional behaviors that follow from the rules above that

policy/common/actor.go

@@ -26,17 +26,17 @@ import (
 // team and organization memberships. The set of allowed actors is the union of
 // all conditions in this structure.
 type Actors struct {
-	Users         []string `yaml:"users"`
-	Teams         []string `yaml:"teams"`
-	Organizations []string `yaml:"organizations"`
+	Users         []string `yaml:"users" json:"users"`
+	Teams         []string `yaml:"teams" json:"teams"`
+	Organizations []string `yaml:"organizations" json:"organizations"`
 
 	// Deprecated: use Permissions with "admin" or "write"
-	Admins             bool `yaml:"admins"`
-	WriteCollaborators bool `yaml:"write_collaborators"`
+	Admins             bool `yaml:"admins" json:"-"`
+	WriteCollaborators bool `yaml:"write_collaborators" json:"-"`
 
 	// A list of GitHub collaborator permissions that are allowed. Values may
 	// be any of "admin", "maintain", "write", "triage", and "read".
-	Permissions []pull.Permission
+	Permissions []pull.Permission `yaml:"permissions" json:"permissions"`
 }
 
 // IsEmpty returns true if no conditions for actors are defined.

policy/simulated/context.go

@@ -0,0 +1,132 @@
+// Copyright 2018 Palantir Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package simulated
+
+import (
+	"context"
+
+	"github.com/palantir/policy-bot/pull"
+)
+
+type Context struct {
+	pull.Context
+	ctx     context.Context
+	options Options
+}
+
+func NewContext(ctx context.Context, pullContext pull.Context, options Options) *Context {
+	return &Context{Context: pullContext, options: options}
+}
+
+func (c *Context) Comments() ([]*pull.Comment, error) {
+	comments, err := c.Context.Comments()
+	if err != nil {
+		return nil, err
+	}
+
+	comments, err = c.filterIgnoredComments(c.Context, comments)
+	if err != nil {
+		return nil, err
+	}
+
+	comments = c.addApprovalComment(comments)
+	return comments, nil
+}
+
+func (c *Context) filterIgnoredComments(prCtx pull.Context, comments []*pull.Comment) ([]*pull.Comment, error) {
+	if c.options.IgnoreComments == nil {
+		return comments, nil
+	}
+
+	var filteredComments []*pull.Comment
+	for _, comment := range comments {
+		isActor, err := c.options.IgnoreComments.IsActor(c.ctx, prCtx, comment.Author)
+		if err != nil {
+			return nil, err
+		}
+
+		if isActor {
+			continue
+		}
+
+		filteredComments = append(filteredComments, comment)
+	}
+
+	return filteredComments, nil
+}
+
+func (c *Context) addApprovalComment(comments []*pull.Comment) []*pull.Comment {
+	var commentsToAdd []*pull.Comment
+	for _, comment := range c.options.AddComments {
+		commentsToAdd = append(commentsToAdd, comment.toPullComment())
+	}
+
+	return append(comments, commentsToAdd...)
+}
+
+func (c *Context) Reviews() ([]*pull.Review, error) {
+	reviews, err := c.Context.Reviews()
+	if err != nil {
+		return nil, err
+	}
+
+	reviews, err = c.filterIgnoredReviews(c.Context, reviews)
+	if err != nil {
+		return nil, err
+	}
+
+	reviews = c.addApprovalReview(reviews)
+	return reviews, nil
+}
+
+func (c *Context) filterIgnoredReviews(prCtx pull.Context, reviews []*pull.Review) ([]*pull.Review, error) {
+	if c.options.IgnoreReviews == nil {
+		return reviews, nil
+	}
+
+	var filteredReviews []*pull.Review
+	for _, review := range reviews {
+		isActor, err := c.options.IgnoreReviews.IsActor(c.ctx, prCtx, review.Author)
+		if err != nil {
+			return nil, err
+		}
+
+		if isActor {
+			continue
+		}
+
+		filteredReviews = append(filteredReviews, review)
+	}
+
+	return filteredReviews, nil
+}
+
+func (c *Context) addApprovalReview(reviews []*pull.Review) []*pull.Review {
+	var reviewsToAdd []*pull.Review
+	for _, review := range c.options.AddReviews {
+		reviewsToAdd = append(reviewsToAdd, review.toPullReview())
+	}
+
+	return append(reviews, reviewsToAdd...)
+}
+
+func (c *Context) Branches() (string, string) {
+	base, head := c.Context.Branches()
+	if c.options.BaseBranch != "" {
+		return c.options.BaseBranch, head
+	}
+
+	return base, head
+}