internal/telemetry/cmd/stacks: add GitHub client

Add a type for a GitHub client.
The type holds the auth token, and its methods are the only way
to access GitHub.

The first of two CLs that will make it possible to test more of this
program, by shunting changes to GitHub off to the side during testing.
(See the following CL for details.)

Change-Id: Ic487714fe75e19b016a132c0eeaaaf74d5c7cd42
Reviewed-on: https://go-review.googlesource.com/c/tools/+/643936
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

Author: jba

gopls/internal/telemetry/cmd/stacks/stacks.go

@@ -99,8 +99,6 @@ var (
 	daysFlag = flag.Int("days", 7, "number of previous days of telemetry data to read")
 
 	dryRun = flag.Bool("n", false, "dry run, avoid updating issues")
-
-	authToken string // mandatory GitHub authentication token (for R/W issues access)
 )
 
 // ProgramConfig is the configuration for processing reports for a specific
@@ -179,6 +177,8 @@ func main() {
 	log.SetPrefix("stacks: ")
 	flag.Parse()
 
+	var ghclient *githubClient
+
 	// Read GitHub authentication token from $HOME/.stacks.token.
 	//
 	// You can create one using the flow at: GitHub > You > Settings >
@@ -198,12 +198,9 @@ func main() {
 		tokenFile := filepath.Join(home, ".stacks.token")
 		content, err := os.ReadFile(tokenFile)
 		if err != nil {
-			if !os.IsNotExist(err) {
-				log.Fatalf("cannot read GitHub authentication token: %v", err)
-			}
-			log.Fatalf("no file %s containing GitHub authentication token.", tokenFile)
+			log.Fatalf("cannot read GitHub authentication token: %v", err)
 		}
-		authToken = string(bytes.TrimSpace(content))
+		ghclient = &githubClient{authToken: string(bytes.TrimSpace(content))}
 	}
 
 	pcfg, ok := programs[*programFlag]
@@ -217,7 +214,7 @@ func main() {
 		log.Fatalf("Error reading reports: %v", err)
 	}
 
-	issues, err := readIssues(pcfg)
+	issues, err := readIssues(ghclient, pcfg)
 	if err != nil {
 		log.Fatalf("Error reading issues: %v", err)
 	}
@@ -226,7 +223,7 @@ func main() {
 	claimedBy := claimStacks(issues, stacks)
 
 	// Update existing issues that claimed new stacks.
-	updateIssues(issues, stacks, stackToURL)
+	updateIssues(ghclient, issues, stacks, stackToURL)
 
 	// For each stack, show existing issue or create a new one.
 	// Aggregate stack IDs by issue summary.
@@ -392,9 +389,9 @@ func readReports(pcfg ProgramConfig, days int) (stacks map[string]map[Info]int64
 
 // readIssues returns all existing issues for the given program and parses any
 // predicates.
-func readIssues(pcfg ProgramConfig) ([]*Issue, error) {
+func readIssues(cli *githubClient, pcfg ProgramConfig) ([]*Issue, error) {
 	// Query GitHub for all existing GitHub issues with the report label.
-	issues, err := searchIssues(pcfg.SearchLabel)
+	issues, err := cli.searchIssues(pcfg.SearchLabel)
 	if err != nil {
 		// TODO(jba): return error instead of dying, or doc.
 		log.Fatalf("GitHub issues label %q search failed: %v", pcfg.SearchLabel, err)
@@ -564,7 +561,7 @@ func claimStacks(issues []*Issue, stacks map[string]map[Info]int64) map[string]*
 }
 
 // updateIssues updates existing issues that claimed new stacks by predicate.
-func updateIssues(issues []*Issue, stacks map[string]map[Info]int64, stackToURL map[string]string) {
+func updateIssues(cli *githubClient, issues []*Issue, stacks map[string]map[Info]int64, stackToURL map[string]string) {
 	for _, issue := range issues {
 		if len(issue.newStacks) == 0 {
 			continue
@@ -580,7 +577,7 @@ func updateIssues(issues []*Issue, stacks map[string]map[Info]int64, stackToURL
 			writeStackComment(comment, stack, id, stackToURL[stack], stacks[stack])
 		}
 
-		if err := addIssueComment(issue.Number, comment.String()); err != nil {
+		if err := cli.addIssueComment(issue.Number, comment.String()); err != nil {
 			log.Println(err)
 			continue
 		}
@@ -593,7 +590,7 @@ func updateIssues(issues []*Issue, stacks map[string]map[Info]int64, stackToURL
 			body += "\nDups:"
 		}
 		body += " " + strings.Join(newStackIDs, " ")
-		if err := updateIssueBody(issue.Number, body); err != nil {
+		if err := cli.updateIssueBody(issue.Number, body); err != nil {
 			log.Printf("added comment to issue #%d but failed to update body: %v",
 				issue.Number, err)
 			continue
@@ -811,10 +808,17 @@ func frameURL(pclntab map[string]FileLine, info Info, frame string) string {
 	return ""
 }
 
+// -- GitHub client --
+
+// A githubClient interacts with GitHub.
+type githubClient struct {
+	authToken string // mandatory GitHub authentication token (for R/W issues access)
+}
+
 // -- GitHub search --
 
 // searchIssues queries the GitHub issue tracker.
-func searchIssues(label string) ([]*Issue, error) {
+func (cli *githubClient) searchIssues(label string) ([]*Issue, error) {
 	label = url.QueryEscape(label)
 
 	// Slurp all issues with the telemetry label.
@@ -833,7 +837,7 @@ func searchIssues(label string) ([]*Issue, error) {
 		if err != nil {
 			return nil, err
 		}
-		req.Header.Add("Authorization", "Bearer "+authToken)
+		req.Header.Add("Authorization", "Bearer "+cli.authToken)
 		resp, err := http.DefaultClient.Do(req)
 		if err != nil {
 			return nil, err
@@ -869,7 +873,7 @@ func searchIssues(label string) ([]*Issue, error) {
 }
 
 // updateIssueBody updates the body of the numbered issue.
-func updateIssueBody(number int, body string) error {
+func (cli *githubClient) updateIssueBody(number int, body string) error {
 	// https://docs.github.com/en/rest/issues/comments#update-an-issue
 	var payload struct {
 		Body string `json:"body"`
@@ -881,14 +885,14 @@ func updateIssueBody(number int, body string) error {
 	}
 
 	url := fmt.Sprintf("https://api.github.com/repos/golang/go/issues/%d", number)
-	if err := requestChange("PATCH", url, data, http.StatusOK); err != nil {
+	if err := cli.requestChange("PATCH", url, data, http.StatusOK); err != nil {
 		return fmt.Errorf("updating issue: %v", err)
 	}
 	return nil
 }
 
 // addIssueComment adds a markdown comment to the numbered issue.
-func addIssueComment(number int, comment string) error {
+func (cli *githubClient) addIssueComment(number int, comment string) error {
 	// https://docs.github.com/en/rest/issues/comments#create-an-issue-comment
 	var payload struct {
 		Body string `json:"body"`
@@ -900,15 +904,15 @@ func addIssueComment(number int, comment string) error {
 	}
 
 	url := fmt.Sprintf("https://api.github.com/repos/golang/go/issues/%d/comments", number)
-	if err := requestChange("POST", url, data, http.StatusCreated); err != nil {
+	if err := cli.requestChange("POST", url, data, http.StatusCreated); err != nil {
 		return fmt.Errorf("creating issue comment: %v", err)
 	}
 	return nil
 }
 
 // requestChange sends a request to url using method, which may change the state at the server.
 // The data is sent as the request body, and wantStatus is the expected response status code.
-func requestChange(method, url string, data []byte, wantStatus int) error {
+func (cli *githubClient) requestChange(method, url string, data []byte, wantStatus int) error {
 	if *dryRun {
 		log.Printf("DRY RUN: %s %s", method, url)
 		return nil
@@ -917,7 +921,7 @@ func requestChange(method, url string, data []byte, wantStatus int) error {
 	if err != nil {
 		return err
 	}
-	req.Header.Add("Authorization", "Bearer "+authToken)
+	req.Header.Add("Authorization", "Bearer "+cli.authToken)
 	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return err