more coverage

Signed-off-by: Nigel Brittain <nbaws@amazon.com>

test/extensions/common/aws/credential_provider_chains_test.cc

@@ -330,6 +330,43 @@ TEST_F(CustomCredentialsProviderChainTest, CreateWebIdentityCredentialProviderOn
       server_context, region, cred_provider, factories);
 }
 
+TEST_F(CustomCredentialsProviderChainTest, WebIdentityNoEnvironmentSession) {
+  NiceMock<MockCustomCredentialsProviderChainFactories> factories;
+  NiceMock<Server::Configuration::MockServerFactoryContext> server_context;
+  Event::SimulatedTimeSystem time_system;
+
+  TestEnvironment::unsetEnvVar("AWS_ROLE_SESSION_NAME");
+  time_system.setSystemTime(std::chrono::milliseconds(1234567890));
+
+  auto region = "ap-southeast-2";
+  auto file_path = TestEnvironment::writeStringToFileForTest("credentials", "hello");
+
+  envoy::extensions::common::aws::v3::AwsCredentialProvider cred_provider = {};
+  cred_provider.mutable_assume_role_with_web_identity_provider()->set_role_arn("arn://1234");
+  cred_provider.mutable_assume_role_with_web_identity_provider()
+      ->mutable_web_identity_token_data_source()
+      ->set_filename(file_path);
+
+  EXPECT_CALL(factories, mockCreateCredentialsFileCredentialsProvider(Ref(server_context), _))
+      .Times(0);
+  std::string role_session_name;
+
+  EXPECT_CALL(factories, createWebIdentityCredentialsProvider(Ref(server_context), _, _, _))
+      .WillOnce(Invoke(WithArg<3>(
+          [&role_session_name](
+              const envoy::extensions::common::aws::v3::AssumeRoleWithWebIdentityCredentialProvider&
+                  provider) -> CredentialsProviderSharedPtr {
+            role_session_name = provider.role_session_name();
+            return nullptr;
+          })));
+
+  auto chain = std::make_shared<Extensions::Common::Aws::CustomCredentialsProviderChain>(
+      server_context, region, cred_provider, factories);
+  // Role session name is equal to nanoseconds from the set simulated system time when environment
+  // variable is unset
+  EXPECT_EQ(role_session_name, "1234567890000000");
+}
+
 TEST_F(CustomCredentialsProviderChainTest, CreateFileAndWebProviders) {
   NiceMock<MockCustomCredentialsProviderChainFactories> factories;
   NiceMock<Server::Configuration::MockServerFactoryContext> server_context;