net/test: Add CertBuilder::GetX509CertificateChain helper.

Provides a more concise method for creating an X509Certificate with the
necessary intermediate(s).

Change-Id: I20d1cedbc7ee177b27871e460b1db56aec8f4e34
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1815994
Commit-Queue: Matt Mueller <mattm@chromium.org>
Reviewed-by: Eric Roman <eroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699051}

net/test/cert_builder.cc

@@ -327,6 +327,17 @@ scoped_refptr<X509Certificate> CertBuilder::GetX509Certificate() {
   return X509Certificate::CreateFromBuffer(DupCertBuffer(), {});
 }
 
+scoped_refptr<X509Certificate> CertBuilder::GetX509CertificateChain() {
+  std::vector<bssl::UniquePtr<CRYPTO_BUFFER>> intermediates;
+  // Add intermediates, not including the self-signed root.
+  for (CertBuilder* cert = issuer_; cert && cert != cert->issuer_;
+       cert = cert->issuer_) {
+    intermediates.push_back(cert->DupCertBuffer());
+  }
+  return X509Certificate::CreateFromBuffer(DupCertBuffer(),
+                                           std::move(intermediates));
+}
+
 std::string CertBuilder::GetDER() {
   return x509_util::CryptoBufferAsStringPiece(GetCertBuffer()).as_string();
 }

net/test/cert_builder.h

@@ -87,6 +87,10 @@ class CertBuilder {
   // Returns an X509Certificate for the generated certificate.
   scoped_refptr<X509Certificate> GetX509Certificate();
 
+  // Returns an X509Certificate for the generated certificate, including
+  // intermediate certificates.
+  scoped_refptr<X509Certificate> GetX509CertificateChain();
+
   // Returns a copy of the certificate's DER.
   std::string GetDER();