diff --git a/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java b/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java
index 29a9459..36db735 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/MethodLibraryTest.java
@@ -346,6 +346,15 @@
   }
 
   @Test
+  public void testCapitalize() throws Exception {
+    new BothModesTest()
+        .testStatement("'hello world'.capitalize()", "Hello world")
+        .testStatement("'HELLO WORLD'.capitalize()", "Hello world")
+        .testStatement("''.capitalize()", "")
+        .testStatement("'12 lower UPPER 34'.capitalize()", "12 lower upper 34");
+  }
+
+  @Test
   public void testPyStringRfind() throws Exception {
     new BothModesTest()
         .testStatement("'banana'.rfind('na')", 4)