Added string len

Shing Lyu · Shing Lyu · commit 99957970affc · 2017-01-26T16:15:07.000+08:00
diff --git a/RustPython/src/builtins.rs b/RustPython/src/builtins.rs
@@ -38,6 +38,7 @@ pub fn len(args: Vec<NativeType>) -> NativeType {
     let len = match &args[0] {
         &NativeType::List(ref l) => l.len(),
         &NativeType::Tuple(ref t) => t.len(),
+        &NativeType::Str(ref s) => s.len(),
         _ => panic!("TypeError: object of this type has no len()")
     };
     NativeType::Int(len as i32)
diff --git a/tests/3.1.2.16.py b/tests/3.1.2.16.py
@@ -0,0 +1,3 @@
+word = "Python"
+assert "on" == word[4:42]
+assert "" == word[42:]
diff --git a/tests/3.1.2.17.py b/tests/3.1.2.17.py
@@ -0,0 +1,7 @@
+word = "Python"
+
+word[0] = "J" # Should raise a error, immutable
+word[2:] = "Jy" # Should raise a error, immutable
+
+
+
diff --git a/tests/3.1.2.18.py b/tests/3.1.2.18.py
@@ -0,0 +1,4 @@
+word = "Python"
+
+assert "Jython" == "J" + word[1:]
+assert "Pypy" == word[:2] + "py"
diff --git a/tests/3.1.2.19.py b/tests/3.1.2.19.py
@@ -0,0 +1,3 @@
+s = "abcdefg"
+
+assert 7 == len(s)
