Add PR branch validation

This  checks  if  the  branch  a  pull  request  is  raised  from  is
non-master.  Validates,  as well,  if a pull request is raised against
the  default  branch.  If the validation  is not successful,  the pull
request is being closed and labels are applied: "review/target-branch"
if the target branch is not  the  default  and  "review/source-branch"
if the source branch is named  "master".  The source branch validation
leaves a warning comment,  suggesting to raise a new pull request from
a named branch

Signed-off-by: Ivana Yovcheva (VMware) <[email protected]>

pullRequestHandler.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"strings"
@@ -30,6 +31,10 @@ func handlePullRequest(req types.PullRequestOuter) {
 
 	client := auth.MakeClient(ctx, token)
 
+	if !passBranchValidation(ctx, req, client) {
+		return
+	}
+
 	hasUnsignedCommits, err := hasUnsigned(req, client)
 
 	if err != nil {
@@ -124,6 +129,91 @@ func hasUnsigned(req types.PullRequestOuter, client *github.Client) (bool, error
 	return hasUnsigned, err
 }
 
+func passBranchValidation(ctx context.Context, req types.PullRequestOuter, client *github.Client) bool {
+	isValidPullRequest := validateHeadBranch(ctx, req, client) && validateBaseBranch(ctx, req, client)
+
+	if !isValidPullRequest {
+		closePullRequest(req)
+	}
+
+	return isValidPullRequest
+}
+
+func validateHeadBranch(ctx context.Context, req types.PullRequestOuter, client *github.Client) bool {
+	if isMasterHeadBranch(req) {
+		body := "Thank you for your contribution. It appears that you are submitting changes directly from your master branch." +
+			"Please raise a new pull request from a named branch i.e. `git checkout -b my_feature`. "
+
+		createComment(ctx, body, req, client)
+
+		applyLabel(ctx, "review/source-branch", req, client)
+	}
+	return !isMasterHeadBranch(req)
+}
+
+func validateBaseBranch(ctx context.Context, req types.PullRequestOuter, client *github.Client) bool {
+	if !isAgainstDefaultBranch(req) {
+		body := "Thank you for your contribution. It appears that you are submitting changes not against the default repository branch." +
+			"Please raise a new pull request againgst the default branch. "
+
+		createComment(ctx, body, req, client)
+
+		applyLabel(ctx, "review/target-branch", req, client)
+	}
+
+	return isAgainstDefaultBranch(req)
+}
+
+func isValidHeadAndBaseBranch(req types.PullRequestOuter) bool {
+	return !isMasterHeadBranch(req) && isAgainstDefaultBranch(req)
+}
+
+func isMasterHeadBranch(req types.PullRequestOuter) bool {
+	return req.GetHeadBranch() == "master"
+}
+
+func isAgainstDefaultBranch(req types.PullRequestOuter) bool {
+	return req.GetDefaultBranch() == req.GetBaseBranch()
+}
+
 func isSigned(msg string) bool {
 	return strings.Contains(msg, "Signed-off-by:")
 }
+
+func createComment(ctx context.Context, body string, req types.PullRequestOuter, client *github.Client) {
+
+	comment := &github.PullRequestComment{
+		Body: &body,
+	}
+
+	client.PullRequests.CreateComment(ctx, req.Repository.Owner.Login, req.Repository.Name, req.PullRequest.Number, comment)
+}
+
+func applyLabel(ctx context.Context, label string, req types.PullRequestOuter, client *github.Client) {
+	fmt.Sprintf("Applying label %s to pull request %d", label, req.PullRequest.Number)
+	_, res, assignLabelErr := client.Issues.AddLabelsToIssue(ctx, req.Repository.Owner.Login, req.Repository.Name, req.PullRequest.Number, []string{label})
+	if assignLabelErr != nil {
+		log.Fatalf("%s limit: %d, remaining: %d", assignLabelErr, res.Limit, res.Remaining)
+	}
+}
+
+func closePullRequest(req types.PullRequestOuter) (string, error) {
+	var buffer bytes.Buffer
+
+	newState, validTransition := checkTransition(closeConstant, req.PullRequest.State)
+
+	if !validTransition {
+		buffer.WriteString(fmt.Sprintf("Cannot close pull request with a %s state", req.PullRequest.State))
+		return buffer.String(), nil
+	}
+
+	input := &github.PullRequest{State: &newState}
+
+	client, ctx := makeClient(req.Installation.ID)
+
+	_, _, err := client.PullRequests.Edit(ctx, req.Repository.Owner.Login, req.Repository.Name, req.PullRequest.Number, input)
+	if err != nil {
+		return buffer.String(), err
+	}
+	return buffer.String(), nil
+}

pullRequestHandler_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"testing"
 
+	"github.com/alexellis/derek/types"
 	"github.com/google/go-github/github"
 )
 
@@ -92,3 +93,99 @@ func Test_hasNoDcoLabel(t *testing.T) {
 		})
 	}
 }
+
+func Test_isValidHeadAndBaseBranch(t *testing.T) {
+
+	pullBranchOptions := []struct {
+		title             string
+		headBranchName    string
+		baseBranchName    string
+		defaultBranchName string
+		expectedResult    bool
+	}{
+		{
+			title:             "Incorrectly named master head branch. Base branch equal to default.",
+			headBranchName:    "master",
+			baseBranchName:    "master",
+			defaultBranchName: "master",
+			expectedResult:    false,
+		},
+		{
+			title:             "Correctly named non-master head branch. Base branch equal to default.",
+			headBranchName:    "test_branch",
+			baseBranchName:    "master",
+			defaultBranchName: "master",
+			expectedResult:    true,
+		},
+		{
+			title:             "Incorrectly named master head branch. Base branch not equal to default.",
+			headBranchName:    "master",
+			baseBranchName:    "master",
+			defaultBranchName: "development",
+			expectedResult:    false,
+		},
+		{
+			title:             "Correctly named non-master head branch. Base branch not equal to default.",
+			headBranchName:    "test_branch",
+			baseBranchName:    "master",
+			defaultBranchName: "development",
+			expectedResult:    false,
+		},
+		{
+			title:             "Correctly named non-master head branch. Base branch not equal to default.",
+			headBranchName:    "development",
+			baseBranchName:    "master",
+			defaultBranchName: "development",
+			expectedResult:    false,
+		},
+		{
+			title:             "Correctly named non-master head branch. Base branch equal to default.",
+			headBranchName:    "development",
+			baseBranchName:    "development",
+			defaultBranchName: "development",
+			expectedResult:    true,
+		},
+		{
+			title:             "Incorrectly named master head branch. Base branch equal to default.",
+			headBranchName:    "master",
+			baseBranchName:    "development",
+			defaultBranchName: "development",
+			expectedResult:    false,
+		},
+		{
+			title:             "Correctly named master head branch. Base branch equal to default.",
+			headBranchName:    "test_branch",
+			baseBranchName:    "development",
+			defaultBranchName: "development",
+			expectedResult:    true,
+		},
+	}
+	for _, test := range pullBranchOptions {
+		t.Run(test.title, func(t *testing.T) {
+			repo := types.Repository{
+				Name:          "test_repo",
+				DefaultBranch: test.defaultBranchName,
+			}
+			headBranch := types.Branch{
+				Repository: repo,
+				Name:       test.headBranchName,
+			}
+			baseBranch := types.Branch{
+				Repository: repo,
+				Name:       test.baseBranchName,
+			}
+			req := types.PullRequestOuter{
+				Repository: repo,
+				BaseBranch: baseBranch,
+				HeadBranch: headBranch,
+			}
+
+			isValidHeadAndBaseBranch := isValidHeadAndBaseBranch(req)
+
+			if isValidHeadAndBaseBranch != test.expectedResult {
+				t.Errorf("Is valid head and base branch (head: %s, base: %s, default: %s) - wanted: %t, found %t",
+					test.headBranchName, test.baseBranchName, test.defaultBranchName, test.expectedResult, isValidHeadAndBaseBranch)
+			}
+		})
+	}
+}

types/types.go

@@ -1,8 +1,14 @@
 package types
 
 type Repository struct {
-	Owner Owner  `json:"owner"`
-	Name  string `json:"name"`
+	Owner         Owner  `json:"owner"`
+	Name          string `json:"name"`
+	DefaultBranch string `json:"default_branch"`
+}
+
+type Branch struct {
+	Repository Repository `json:"repository"`
+	Name       string     `json:"ref"`
 }
 
 type Owner struct {
@@ -11,7 +17,8 @@ type Owner struct {
 }
 
 type PullRequest struct {
-	Number int `json:"number"`
+	Number int    `json:"number"`
+	State  string `json:"state"`
 }
 
 type InstallationRequest struct {
@@ -25,10 +32,24 @@ type ID struct {
 type PullRequestOuter struct {
 	Repository  Repository  `json:"repository"`
 	PullRequest PullRequest `json:"pull_request"`
+	BaseBranch  Branch      `json:"base"`
+	HeadBranch  Branch      `json:"head"`
 	Action      string      `json:"action"`
 	InstallationRequest
 }
 
+func (req *PullRequestOuter) GetDefaultBranch() string {
+	return req.Repository.DefaultBranch
+}
+
+func (req *PullRequestOuter) GetBaseBranch() string {
+	return req.BaseBranch.Name
+}
+
+func (req *PullRequestOuter) GetHeadBranch() string {
+	return req.HeadBranch.Name
+}
+
 type IssueCommentOuter struct {
 	Repository Repository `json:"repository"`
 	Comment    Comment    `json:"comment"`