test(tool/cmd/migrate): add test to fetchGoogleapisWithCommit (#4550)

Add test to fetchGoogleapisWithCommit. For
#4514 (comment)

Author: zhumin8

tool/cmd/migrate/java.go

@@ -136,7 +136,7 @@ func runJavaMigration(ctx context.Context, repoPath string) error {
 	if commit == "" {
 		commit = "master"
 	}
-	src, err := fetchSourceWithCommit(ctx, commit)
+	src, err := fetchSourceWithCommit(ctx, githubEndpoints, commit)
 	if err != nil {
 		return errFetchSource
 	}

tool/cmd/migrate/java_test.go

@@ -22,10 +22,11 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/googleapis/librarian/internal/config"
+	"github.com/googleapis/librarian/internal/fetch"
 )
 
 func TestRunJavaMigration(t *testing.T) {
-	fetchSourceWithCommit = func(ctx context.Context, commitish string) (*config.Source, error) {
+	fetchSourceWithCommit = func(ctx context.Context, endpoints *fetch.Endpoints, commitish string) (*config.Source, error) {
 		return &config.Source{
 			Commit: commitish,
 			SHA256: "sha123",

tool/cmd/migrate/legacylibrarian.go

@@ -43,6 +43,11 @@ var (
 		"logging":  "logadmin",
 		"pubsub":   "v2",
 	}
+
+	githubEndpoints = &fetch.Endpoints{
+		API:      "https://api.github.com",
+		Download: "https://github.com",
+	}
 )
 
 type goGAPICInfo struct {
@@ -177,20 +182,16 @@ func buildConfigFromLibrarian(ctx context.Context, input *MigrationInput) (*conf
 }
 
 func fetchGoogleapis(ctx context.Context) (*config.Source, error) {
-	return fetchGoogleapisWithCommit(ctx, fetch.DefaultBranchMaster)
+	return fetchGoogleapisWithCommit(ctx, githubEndpoints, fetch.DefaultBranchMaster)
 }
 
-func fetchGoogleapisWithCommit(ctx context.Context, commitish string) (*config.Source, error) {
-	endpoint := &fetch.Endpoints{
-		API:      "https://api.github.com",
-		Download: "https://github.com",
-	}
+func fetchGoogleapisWithCommit(ctx context.Context, endpoints *fetch.Endpoints, commitish string) (*config.Source, error) {
 	repo := &fetch.Repo{
 		Org:    "googleapis",
 		Repo:   "googleapis",
 		Branch: commitish,
 	}
-	commit, sha256, err := fetch.LatestCommitAndChecksum(endpoint, repo)
+	commit, sha256, err := fetch.LatestCommitAndChecksum(endpoints, repo)
 	if err != nil {
 		return nil, err
 	}

tool/cmd/migrate/legacylibrarian_test.go

@@ -17,13 +17,18 @@ package main
 import (
 	"context"
 	"errors"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
 	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/googleapis/librarian/internal/config"
+	"github.com/googleapis/librarian/internal/fetch"
 	"github.com/googleapis/librarian/internal/legacylibrarian/legacyconfig"
 )
 
@@ -935,3 +940,52 @@ func TestToAPIs(t *testing.T) {
 		t.Errorf("mismatch (-want +got):\n%s", diff)
 	}
 }
+
+func TestFetchGoogleapisWithCommit(t *testing.T) {
+	const (
+		wantCommit = "abcd123"
+		wantSHA    = "5e884898da28047151d0e56f8dc6292773603d0d6aabbdd62a11ef721d1542d8" // sha256 of "password"
+	)
+	// Mock GitHub server
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if strings.Contains(r.URL.Path, "/commits/") {
+			w.Write([]byte(wantCommit))
+			return
+		}
+		if strings.Contains(r.URL.Path, ".tar.gz") {
+			w.Write([]byte("password"))
+			return
+		}
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer ts.Close()
+	endpoints := &fetch.Endpoints{
+		API:      ts.URL,
+		Download: ts.URL,
+	}
+	// Mock cache
+	tmp := t.TempDir()
+	t.Setenv("LIBRARIAN_CACHE", tmp)
+	// Pre-populate cache to avoid RepoDir downloading (which ignores our mock download URL)
+	cachePath := filepath.Join(tmp, fmt.Sprintf("%s@%s", googleapisRepo, wantCommit))
+	if err := os.MkdirAll(cachePath, 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(cachePath, "dummy"), []byte("dummy"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := fetchGoogleapisWithCommit(t.Context(), endpoints, "master")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	want := &config.Source{
+		Commit: wantCommit,
+		SHA256: wantSHA,
+		Dir:    cachePath,
+	}
+	if diff := cmp.Diff(want, got); diff != "" {
+		t.Errorf("mismatch (-want +got):\n%s", diff)
+	}
+}