content,internal: use test ids in unit meta server tests

Updates server tests for recent changes to the unit
meta section. Uses data-test-ids instead of css class
selectors to make tests easier to maintain when html
structure or classnames are changed.

Change-Id: I4d17179e49f101865f9932c47552038e127df106
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/308149
Reviewed-by: Julie Qiu <julie@golang.org>
Trust: Jamal Carvalho <jamal@golang.org>

content/static/html/helpers/_unit_meta.tmpl

@@ -39,7 +39,8 @@
 {{define "unit_meta_links"}}
   {{range .}}
     <li>
-      <a href="{{.Href}}" title="{{.Href}}" target="_blank" rel="noopener">{{.Body}}</a>
+      <a href="{{.Href}}" title="{{.Href}}" target="_blank" rel="noopener"
+          data-test-id="meta-link-{{.Body}}">{{.Body}}</a>
     </li>
   {{end}}
 {{end}}

internal/frontend/server_test.go

@@ -1076,10 +1076,10 @@ func serverTestCases() []serverTestCase {
 	}
 }
 
-func checkLink(n int, title, url string) htmlcheck.Checker {
+func checkLink(title, url string) htmlcheck.Checker {
 	// The first div under .UnitMeta is "Repository", the second is "Links",
 	// and each subsequent div contains a <a> tag with a custom link.
-	return in(fmt.Sprintf("div:nth-of-type(%d) > a", n+2), href(url), hasText(title))
+	return in(fmt.Sprintf(`[data-test-id="meta-link-%s"]`, title), href(url), hasText(title))
 }
 
 var linksTestCases = []serverTestCase{
@@ -1087,36 +1087,36 @@ var linksTestCases = []serverTestCase{
 		name:           "module links",
 		urlPath:        "/github.com/links/mod",
 		wantStatusCode: http.StatusOK,
-		want: in(".UnitMeta",
+		want: in("",
 			// Module readme links.
-			checkLink(1, "title1", "http://url1"),
-			checkLink(2, "title2", "about:invalid#zGoSafez"),
+			checkLink("title1", "http://url1"),
+			checkLink("title2", "about:invalid#zGoSafez"),
 		),
 	},
 	{
 		name:           "no_readme package links",
 		urlPath:        "/github.com/links/mod/no_readme",
 		wantStatusCode: http.StatusOK,
-		want: in(".UnitMeta",
+		want: in("",
 			// Package doc links are first.
-			checkLink(1, "pkg.go.dev", "https://pkg.go.dev"),
+			checkLink("pkg.go.dev", "https://pkg.go.dev"),
 			// Then module readmes.
-			checkLink(2, "title1", "http://url1"),
-			checkLink(3, "title2", "about:invalid#zGoSafez"),
+			checkLink("title1", "http://url1"),
+			checkLink("title2", "about:invalid#zGoSafez"),
 		),
 	},
 	{
 		name:           "has_readme package links",
 		urlPath:        "/github.com/links/mod/has_readme",
 		wantStatusCode: http.StatusOK,
-		want: in(".UnitMeta",
+		want: in("",
 			// Package readme links are first.
-			checkLink(1, "pkg title", "http://url2"),
+			checkLink("pkg title", "http://url2"),
 			// Package doc links are second.
-			checkLink(2, "pkg.go.dev", "https://pkg.go.dev"),
+			checkLink("pkg.go.dev", "https://pkg.go.dev"),
 			// Module readme links are third.
-			checkLink(3, "title1", "http://url1"),
-			checkLink(4, "title2", "about:invalid#zGoSafez"),
+			checkLink("title1", "http://url1"),
+			checkLink("title2", "about:invalid#zGoSafez"),
 		),
 	},
 	{