title: gtest: check if string is equal to one of two strings
body: <p>Consider that I have two strings:</p>
  
  <pre><code>std::string s1 = "ab"; 
  std::string s2 = "cd";
  </code></pre>
  
  <p>and I want to check (e.g. using EXPECT_EQ) if some given <code>std::string str</code> is equal either to <code>s1</code> or <code>s2</code>.</p>
  
  <p>If gtest's <code>ASSERT_*</code> and <code>EXPECT_*</code> would return <code>bool</code> I could have written</p>
  
  <pre><code>EXPECT_TRUE(EXPECT_EQ(str, s1) || EXPECT_EQ(str, s2));
  </code></pre>
  
  <p>but, unfortunately, they don't.</p>