internal/proxy: clean versions returned with spaces

jFrog Artifactory's go module proxy incorrectly responds to /@v/list with
versions that all have a space suffix ("v1.2.3 " instead of "v1.2.3").
Currently, this causes an issue when we take that version and we try to add
things like ".info", resulting in URLs like GET "foo.com/v1.2.3 .info" instead
of "foo.com/v1.2.3.info".

This change cleans up versions with such a suffix to fix this issue, and adds
a test (and the ability to test) for this situation.

Fixes golang/go#71141

Change-Id: I12d188f736258b5e263e007c6f757b15fd47545d
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/640655
Reviewed-by: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Jonathan Amsterdam <[email protected]>
kokoro-CI: kokoro <[email protected]>

internal/proxy/client.go

@@ -229,7 +229,7 @@ func (c *Client) Versions(ctx context.Context, modulePath string) (_ []string, e
 	collect := func(body io.Reader) error {
 		scanner := bufio.NewScanner(body)
 		for scanner.Scan() {
-			versions = append(versions, scanner.Text())
+			versions = append(versions, strings.TrimSpace(scanner.Text()))
 		}
 		return scanner.Err()
 	}

internal/proxy/client_test.go

@@ -110,11 +110,16 @@ func TestListVersions(t *testing.T) {
 			Version:    "v1.3.0",
 			Files:      map[string]string{"bar.go": "package bar\nconst Version = 1.3"},
 		},
+		{
+			ModulePath: sample.ModulePath,
+			Version:    "v1.4.0 ",
+			Files:      map[string]string{"bar.go": "package bar\nconst Version = 1.4"},
+		},
 	}
 	client, teardownProxy := proxytest.SetupTestClient(t, testModules)
 	defer teardownProxy()
 
-	want := []string{"v1.1.0", "v1.2.0"}
+	want := []string{"v1.4.0", "v1.1.0", "v1.2.0"}
 	got, err := client.Versions(ctx, sample.ModulePath)
 	if err != nil {
 		t.Fatal(err)

internal/proxy/proxytest/module.go

@@ -5,7 +5,10 @@
 // Package proxytest supports testing with the proxy.
 package proxytest
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 // Module represents a module version used by the proxy server.
 type Module struct {
@@ -16,6 +19,13 @@ type Module struct {
 	zip        []byte
 }
 
+// Some module proxies incorrectly return a space after the version. Tests may
+// simulate that that behavior by giving m.Version a space suffix. This function
+// will always, however, return the correct form for the version.
+func (m *Module) TidyVersion() string {
+	return strings.TrimSpace(m.Version)
+}
+
 // ChangePath returns a copy of m with a different module path.
 func (m *Module) ChangePath(modulePath string) *Module {
 	m2 := *m

internal/proxy/proxytest/server.go

@@ -71,15 +71,15 @@ func (s *Server) handleMod(m *Module) {
 	if goMod == "" {
 		goMod = defaultGoMod(m.ModulePath)
 	}
-	s.mux.HandleFunc(fmt.Sprintf("/%s/@v/%s.mod", m.ModulePath, m.Version),
+	s.mux.HandleFunc(fmt.Sprintf("/%s/@v/%s.mod", m.ModulePath, m.TidyVersion()),
 		func(w http.ResponseWriter, r *http.Request) {
 			http.ServeContent(w, r, m.ModulePath, time.Now(), strings.NewReader(goMod))
 		})
 }
 
 // handleZip creates a zip endpoint for the specified module version.
 func (s *Server) handleZip(m *Module) {
-	s.mux.HandleFunc(fmt.Sprintf("/%s/@v/%s.zip", m.ModulePath, m.Version),
+	s.mux.HandleFunc(fmt.Sprintf("/%s/@v/%s.zip", m.ModulePath, m.TidyVersion()),
 		func(w http.ResponseWriter, r *http.Request) {
 			s.mu.Lock()
 			s.zipRequests++
@@ -150,7 +150,7 @@ func (s *Server) addModule(m *Module, hasVersions bool) {
 			})
 		}
 	}
-	s.handleInfo(m.ModulePath, m.Version, m.NotCached)
+	s.handleInfo(m.ModulePath, m.TidyVersion(), m.NotCached)
 	s.handleMod(m)
 	s.handleZip(m)