diff --git a/src/libcoretest/cell.rs b/src/libcoretest/cell.rs
index 6444cf7ee0ebfea3243d51c23a4c6b32ca69b052..54da6264bb0491e1f947250c7f723c2c73ebe557 100644
--- a/src/libcoretest/cell.rs
+++ b/src/libcoretest/cell.rs
@@ -29,10 +29,10 @@ fn smoketest_cell() {
 #[test]
 fn cell_has_sensible_show() {
     let x = Cell::new("foo bar");
-    assert!(format!("{}", x).as_slice().contains(x.get()));
+    assert!(format!("{}", x).contains(x.get()));
 
     x.set("baz qux");
-    assert!(format!("{}", x).as_slice().contains(x.get()));
+    assert!(format!("{}", x).contains(x.get()));
 }
 
 #[test]
@@ -40,11 +40,11 @@ fn ref_and_refmut_have_sensible_show() {
     let refcell = RefCell::new("foo");
 
     let refcell_refmut = refcell.borrow_mut();
-    assert!(format!("{}", refcell_refmut).as_slice().contains("foo"));
+    assert!(format!("{}", refcell_refmut).contains("foo"));
     drop(refcell_refmut);
 
     let refcell_ref = refcell.borrow();
-    assert!(format!("{}", refcell_ref).as_slice().contains("foo"));
+    assert!(format!("{}", refcell_ref).contains("foo"));
     drop(refcell_ref);
 }
 
diff --git a/src/libcoretest/char.rs b/src/libcoretest/char.rs
index 507ddf65e55b35c9dca1b4a6d72053bc68620346..e5561bebb22d8927c8fb62e71b9f6095f5c623cb 100644
--- a/src/libcoretest/char.rs
+++ b/src/libcoretest/char.rs
@@ -121,31 +121,31 @@ fn string(c: char) -> String {
         return result;
     }
     let s = string('\n');
-    assert_eq!(s.as_slice(), "\\n");
+    assert_eq!(s, "\\n");
     let s = string('\r');
-    assert_eq!(s.as_slice(), "\\r");
+    assert_eq!(s, "\\r");
     let s = string('\'');
-    assert_eq!(s.as_slice(), "\\'");
+    assert_eq!(s, "\\'");
     let s = string('"');
-    assert_eq!(s.as_slice(), "\\\"");
+    assert_eq!(s, "\\\"");
     let s = string(' ');
-    assert_eq!(s.as_slice(), " ");
+    assert_eq!(s, " ");
     let s = string('a');
-    assert_eq!(s.as_slice(), "a");
+    assert_eq!(s, "a");
     let s = string('~');
-    assert_eq!(s.as_slice(), "~");
+    assert_eq!(s, "~");
     let s = string('\x00');
-    assert_eq!(s.as_slice(), "\\x00");
+    assert_eq!(s, "\\x00");
     let s = string('\x1f');
-    assert_eq!(s.as_slice(), "\\x1f");
+    assert_eq!(s, "\\x1f");
     let s = string('\x7f');
-    assert_eq!(s.as_slice(), "\\x7f");
+    assert_eq!(s, "\\x7f");
     let s = string('\u00ff');
-    assert_eq!(s.as_slice(), "\\u00ff");
+    assert_eq!(s, "\\u00ff");
     let s = string('\u011b');
-    assert_eq!(s.as_slice(), "\\u011b");
+    assert_eq!(s, "\\u011b");
     let s = string('\U0001d4b6');
-    assert_eq!(s.as_slice(), "\\U0001d4b6");
+    assert_eq!(s, "\\U0001d4b6");
 }
 
 #[test]
@@ -156,17 +156,17 @@ fn string(c: char) -> String {
         return result;
     }
     let s = string('\x00');
-    assert_eq!(s.as_slice(), "\\x00");
+    assert_eq!(s, "\\x00");
     let s = string('\n');
-    assert_eq!(s.as_slice(), "\\x0a");
+    assert_eq!(s, "\\x0a");
     let s = string(' ');
-    assert_eq!(s.as_slice(), "\\x20");
+    assert_eq!(s, "\\x20");
     let s = string('a');
-    assert_eq!(s.as_slice(), "\\x61");
+    assert_eq!(s, "\\x61");
     let s = string('\u011b');
-    assert_eq!(s.as_slice(), "\\u011b");
+    assert_eq!(s, "\\u011b");
     let s = string('\U0001d4b6');
-    assert_eq!(s.as_slice(), "\\U0001d4b6");
+    assert_eq!(s, "\\U0001d4b6");
 }
 
 #[test]
diff --git a/src/libcoretest/fmt/num.rs b/src/libcoretest/fmt/num.rs
index 3b43d6ad33b4429c4b6b210938a2da05891eb020..1e28933becd6ec6808011712ca09e77f76aac57d 100644
--- a/src/libcoretest/fmt/num.rs
+++ b/src/libcoretest/fmt/num.rs
@@ -16,136 +16,136 @@ fn test_format_int() {
     // Formatting integers should select the right implementation based off
     // the type of the argument. Also, hex/octal/binary should be defined
     // for integers, but they shouldn't emit the negative sign.
-    assert!(format!("{}", 1i).as_slice() == "1");
-    assert!(format!("{}", 1i8).as_slice() == "1");
-    assert!(format!("{}", 1i16).as_slice() == "1");
-    assert!(format!("{}", 1i32).as_slice() == "1");
-    assert!(format!("{}", 1i64).as_slice() == "1");
-    assert!(format!("{}", -1i).as_slice() == "-1");
-    assert!(format!("{}", -1i8).as_slice() == "-1");
-    assert!(format!("{}", -1i16).as_slice() == "-1");
-    assert!(format!("{}", -1i32).as_slice() == "-1");
-    assert!(format!("{}", -1i64).as_slice() == "-1");
-    assert!(format!("{:b}", 1i).as_slice() == "1");
-    assert!(format!("{:b}", 1i8).as_slice() == "1");
-    assert!(format!("{:b}", 1i16).as_slice() == "1");
-    assert!(format!("{:b}", 1i32).as_slice() == "1");
-    assert!(format!("{:b}", 1i64).as_slice() == "1");
-    assert!(format!("{:x}", 1i).as_slice() == "1");
-    assert!(format!("{:x}", 1i8).as_slice() == "1");
-    assert!(format!("{:x}", 1i16).as_slice() == "1");
-    assert!(format!("{:x}", 1i32).as_slice() == "1");
-    assert!(format!("{:x}", 1i64).as_slice() == "1");
-    assert!(format!("{:X}", 1i).as_slice() == "1");
-    assert!(format!("{:X}", 1i8).as_slice() == "1");
-    assert!(format!("{:X}", 1i16).as_slice() == "1");
-    assert!(format!("{:X}", 1i32).as_slice() == "1");
-    assert!(format!("{:X}", 1i64).as_slice() == "1");
-    assert!(format!("{:o}", 1i).as_slice() == "1");
-    assert!(format!("{:o}", 1i8).as_slice() == "1");
-    assert!(format!("{:o}", 1i16).as_slice() == "1");
-    assert!(format!("{:o}", 1i32).as_slice() == "1");
-    assert!(format!("{:o}", 1i64).as_slice() == "1");
-
-    assert!(format!("{}", 1u).as_slice() == "1");
-    assert!(format!("{}", 1u8).as_slice() == "1");
-    assert!(format!("{}", 1u16).as_slice() == "1");
-    assert!(format!("{}", 1u32).as_slice() == "1");
-    assert!(format!("{}", 1u64).as_slice() == "1");
-    assert!(format!("{:b}", 1u).as_slice() == "1");
-    assert!(format!("{:b}", 1u8).as_slice() == "1");
-    assert!(format!("{:b}", 1u16).as_slice() == "1");
-    assert!(format!("{:b}", 1u32).as_slice() == "1");
-    assert!(format!("{:b}", 1u64).as_slice() == "1");
-    assert!(format!("{:x}", 1u).as_slice() == "1");
-    assert!(format!("{:x}", 1u8).as_slice() == "1");
-    assert!(format!("{:x}", 1u16).as_slice() == "1");
-    assert!(format!("{:x}", 1u32).as_slice() == "1");
-    assert!(format!("{:x}", 1u64).as_slice() == "1");
-    assert!(format!("{:X}", 1u).as_slice() == "1");
-    assert!(format!("{:X}", 1u8).as_slice() == "1");
-    assert!(format!("{:X}", 1u16).as_slice() == "1");
-    assert!(format!("{:X}", 1u32).as_slice() == "1");
-    assert!(format!("{:X}", 1u64).as_slice() == "1");
-    assert!(format!("{:o}", 1u).as_slice() == "1");
-    assert!(format!("{:o}", 1u8).as_slice() == "1");
-    assert!(format!("{:o}", 1u16).as_slice() == "1");
-    assert!(format!("{:o}", 1u32).as_slice() == "1");
-    assert!(format!("{:o}", 1u64).as_slice() == "1");
+    assert!(format!("{}", 1i) == "1");
+    assert!(format!("{}", 1i8) == "1");
+    assert!(format!("{}", 1i16) == "1");
+    assert!(format!("{}", 1i32) == "1");
+    assert!(format!("{}", 1i64) == "1");
+    assert!(format!("{}", -1i) == "-1");
+    assert!(format!("{}", -1i8) == "-1");
+    assert!(format!("{}", -1i16) == "-1");
+    assert!(format!("{}", -1i32) == "-1");
+    assert!(format!("{}", -1i64) == "-1");
+    assert!(format!("{:b}", 1i) == "1");
+    assert!(format!("{:b}", 1i8) == "1");
+    assert!(format!("{:b}", 1i16) == "1");
+    assert!(format!("{:b}", 1i32) == "1");
+    assert!(format!("{:b}", 1i64) == "1");
+    assert!(format!("{:x}", 1i) == "1");
+    assert!(format!("{:x}", 1i8) == "1");
+    assert!(format!("{:x}", 1i16) == "1");
+    assert!(format!("{:x}", 1i32) == "1");
+    assert!(format!("{:x}", 1i64) == "1");
+    assert!(format!("{:X}", 1i) == "1");
+    assert!(format!("{:X}", 1i8) == "1");
+    assert!(format!("{:X}", 1i16) == "1");
+    assert!(format!("{:X}", 1i32) == "1");
+    assert!(format!("{:X}", 1i64) == "1");
+    assert!(format!("{:o}", 1i) == "1");
+    assert!(format!("{:o}", 1i8) == "1");
+    assert!(format!("{:o}", 1i16) == "1");
+    assert!(format!("{:o}", 1i32) == "1");
+    assert!(format!("{:o}", 1i64) == "1");
+
+    assert!(format!("{}", 1u) == "1");
+    assert!(format!("{}", 1u8) == "1");
+    assert!(format!("{}", 1u16) == "1");
+    assert!(format!("{}", 1u32) == "1");
+    assert!(format!("{}", 1u64) == "1");
+    assert!(format!("{:b}", 1u) == "1");
+    assert!(format!("{:b}", 1u8) == "1");
+    assert!(format!("{:b}", 1u16) == "1");
+    assert!(format!("{:b}", 1u32) == "1");
+    assert!(format!("{:b}", 1u64) == "1");
+    assert!(format!("{:x}", 1u) == "1");
+    assert!(format!("{:x}", 1u8) == "1");
+    assert!(format!("{:x}", 1u16) == "1");
+    assert!(format!("{:x}", 1u32) == "1");
+    assert!(format!("{:x}", 1u64) == "1");
+    assert!(format!("{:X}", 1u) == "1");
+    assert!(format!("{:X}", 1u8) == "1");
+    assert!(format!("{:X}", 1u16) == "1");
+    assert!(format!("{:X}", 1u32) == "1");
+    assert!(format!("{:X}", 1u64) == "1");
+    assert!(format!("{:o}", 1u) == "1");
+    assert!(format!("{:o}", 1u8) == "1");
+    assert!(format!("{:o}", 1u16) == "1");
+    assert!(format!("{:o}", 1u32) == "1");
+    assert!(format!("{:o}", 1u64) == "1");
 
     // Test a larger number
-    assert!(format!("{:b}", 55i).as_slice() == "110111");
-    assert!(format!("{:o}", 55i).as_slice() == "67");
-    assert!(format!("{}", 55i).as_slice() == "55");
-    assert!(format!("{:x}", 55i).as_slice() == "37");
-    assert!(format!("{:X}", 55i).as_slice() == "37");
+    assert!(format!("{:b}", 55i) == "110111");
+    assert!(format!("{:o}", 55i) == "67");
+    assert!(format!("{}", 55i) == "55");
+    assert!(format!("{:x}", 55i) == "37");
+    assert!(format!("{:X}", 55i) == "37");
 }
 
 #[test]
 fn test_format_int_zero() {
-    assert!(format!("{}", 0i).as_slice() == "0");
-    assert!(format!("{:b}", 0i).as_slice() == "0");
-    assert!(format!("{:o}", 0i).as_slice() == "0");
-    assert!(format!("{:x}", 0i).as_slice() == "0");
-    assert!(format!("{:X}", 0i).as_slice() == "0");
-
-    assert!(format!("{}", 0u).as_slice() == "0");
-    assert!(format!("{:b}", 0u).as_slice() == "0");
-    assert!(format!("{:o}", 0u).as_slice() == "0");
-    assert!(format!("{:x}", 0u).as_slice() == "0");
-    assert!(format!("{:X}", 0u).as_slice() == "0");
+    assert!(format!("{}", 0i) == "0");
+    assert!(format!("{:b}", 0i) == "0");
+    assert!(format!("{:o}", 0i) == "0");
+    assert!(format!("{:x}", 0i) == "0");
+    assert!(format!("{:X}", 0i) == "0");
+
+    assert!(format!("{}", 0u) == "0");
+    assert!(format!("{:b}", 0u) == "0");
+    assert!(format!("{:o}", 0u) == "0");
+    assert!(format!("{:x}", 0u) == "0");
+    assert!(format!("{:X}", 0u) == "0");
 }
 
 #[test]
 fn test_format_int_flags() {
-    assert!(format!("{:3}", 1i).as_slice() == "  1");
-    assert!(format!("{:>3}", 1i).as_slice() == "  1");
-    assert!(format!("{:>+3}", 1i).as_slice() == " +1");
-    assert!(format!("{:<3}", 1i).as_slice() == "1  ");
-    assert!(format!("{:#}", 1i).as_slice() == "1");
-    assert!(format!("{:#x}", 10i).as_slice() == "0xa");
-    assert!(format!("{:#X}", 10i).as_slice() == "0xA");
-    assert!(format!("{:#5x}", 10i).as_slice() == "  0xa");
-    assert!(format!("{:#o}", 10i).as_slice() == "0o12");
-    assert!(format!("{:08x}", 10i).as_slice() == "0000000a");
-    assert!(format!("{:8x}", 10i).as_slice() == "       a");
-    assert!(format!("{:<8x}", 10i).as_slice() == "a       ");
-    assert!(format!("{:>8x}", 10i).as_slice() == "       a");
-    assert!(format!("{:#08x}", 10i).as_slice() == "0x00000a");
-    assert!(format!("{:08}", -10i).as_slice() == "-0000010");
-    assert!(format!("{:x}", -1u8).as_slice() == "ff");
-    assert!(format!("{:X}", -1u8).as_slice() == "FF");
-    assert!(format!("{:b}", -1u8).as_slice() == "11111111");
-    assert!(format!("{:o}", -1u8).as_slice() == "377");
-    assert!(format!("{:#x}", -1u8).as_slice() == "0xff");
-    assert!(format!("{:#X}", -1u8).as_slice() == "0xFF");
-    assert!(format!("{:#b}", -1u8).as_slice() == "0b11111111");
-    assert!(format!("{:#o}", -1u8).as_slice() == "0o377");
+    assert!(format!("{:3}", 1i) == "  1");
+    assert!(format!("{:>3}", 1i) == "  1");
+    assert!(format!("{:>+3}", 1i) == " +1");
+    assert!(format!("{:<3}", 1i) == "1  ");
+    assert!(format!("{:#}", 1i) == "1");
+    assert!(format!("{:#x}", 10i) == "0xa");
+    assert!(format!("{:#X}", 10i) == "0xA");
+    assert!(format!("{:#5x}", 10i) == "  0xa");
+    assert!(format!("{:#o}", 10i) == "0o12");
+    assert!(format!("{:08x}", 10i) == "0000000a");
+    assert!(format!("{:8x}", 10i) == "       a");
+    assert!(format!("{:<8x}", 10i) == "a       ");
+    assert!(format!("{:>8x}", 10i) == "       a");
+    assert!(format!("{:#08x}", 10i) == "0x00000a");
+    assert!(format!("{:08}", -10i) == "-0000010");
+    assert!(format!("{:x}", -1u8) == "ff");
+    assert!(format!("{:X}", -1u8) == "FF");
+    assert!(format!("{:b}", -1u8) == "11111111");
+    assert!(format!("{:o}", -1u8) == "377");
+    assert!(format!("{:#x}", -1u8) == "0xff");
+    assert!(format!("{:#X}", -1u8) == "0xFF");
+    assert!(format!("{:#b}", -1u8) == "0b11111111");
+    assert!(format!("{:#o}", -1u8) == "0o377");
 }
 
 #[test]
 fn test_format_int_sign_padding() {
-    assert!(format!("{:+5}", 1i).as_slice() == "   +1");
-    assert!(format!("{:+5}", -1i).as_slice() == "   -1");
-    assert!(format!("{:05}", 1i).as_slice() == "00001");
-    assert!(format!("{:05}", -1i).as_slice() == "-0001");
-    assert!(format!("{:+05}", 1i).as_slice() == "+0001");
-    assert!(format!("{:+05}", -1i).as_slice() == "-0001");
+    assert!(format!("{:+5}", 1i) == "   +1");
+    assert!(format!("{:+5}", -1i) == "   -1");
+    assert!(format!("{:05}", 1i) == "00001");
+    assert!(format!("{:05}", -1i) == "-0001");
+    assert!(format!("{:+05}", 1i) == "+0001");
+    assert!(format!("{:+05}", -1i) == "-0001");
 }
 
 #[test]
 fn test_format_int_twos_complement() {
     use core::{i8, i16, i32, i64};
-    assert!(format!("{}", i8::MIN).as_slice() == "-128");
-    assert!(format!("{}", i16::MIN).as_slice() == "-32768");
-    assert!(format!("{}", i32::MIN).as_slice() == "-2147483648");
-    assert!(format!("{}", i64::MIN).as_slice() == "-9223372036854775808");
+    assert!(format!("{}", i8::MIN) == "-128");
+    assert!(format!("{}", i16::MIN) == "-32768");
+    assert!(format!("{}", i32::MIN) == "-2147483648");
+    assert!(format!("{}", i64::MIN) == "-9223372036854775808");
 }
 
 #[test]
 fn test_format_radix() {
-    assert!(format!("{:04}", radix(3i, 2)).as_slice() == "0011");
-    assert!(format!("{}", radix(55i, 36)).as_slice() == "1j");
+    assert!(format!("{:04}", radix(3i, 2)) == "0011");
+    assert!(format!("{}", radix(55i, 36)) == "1j");
 }
 
 #[test]
diff --git a/src/libcoretest/option.rs b/src/libcoretest/option.rs
index a5927d47eb0af70b1605fc85e7c6212ba5720d8f..86fc25c9d918c2b765a2fe26645e0ec299668e0e 100644
--- a/src/libcoretest/option.rs
+++ b/src/libcoretest/option.rs
@@ -28,10 +28,10 @@ fn test_get_ptr() {
 #[test]
 fn test_get_str() {
     let x = "test".to_string();
-    let addr_x = x.as_slice().as_ptr();
+    let addr_x = x.as_ptr();
     let opt = Some(x);
     let y = opt.unwrap();
-    let addr_y = y.as_slice().as_ptr();
+    let addr_y = y.as_ptr();
     assert_eq!(addr_x, addr_y);
 }
 
@@ -135,7 +135,7 @@ fn test_or_else() {
 fn test_unwrap() {
     assert_eq!(Some(1i).unwrap(), 1);
     let s = Some("hello".to_string()).unwrap();
-    assert_eq!(s.as_slice(), "hello");
+    assert_eq!(s, "hello");
 }
 
 #[test]
@@ -266,4 +266,4 @@ fn test_cloned() {
     assert_eq!(opt_ref_ref.clone(), Some(&val1_ref));
     assert_eq!(opt_ref_ref.clone().cloned(), Some(&val1));
     assert_eq!(opt_ref_ref.cloned().cloned(), Some(1u32));
-}
\ No newline at end of file
+}
diff --git a/src/libcoretest/result.rs b/src/libcoretest/result.rs
index 92124e2f299cd9c730ac793a6e468ca3ef2e8311..415cd4e7dcfb80a75c05be7cf77452d6062bf703 100644
--- a/src/libcoretest/result.rs
+++ b/src/libcoretest/result.rs
@@ -93,9 +93,9 @@ pub fn test_fmt_default() {
     let err: Result<int, &'static str> = Err("Err");
 
     let s = format!("{}", ok);
-    assert_eq!(s.as_slice(), "Ok(100)");
+    assert_eq!(s, "Ok(100)");
     let s = format!("{}", err);
-    assert_eq!(s.as_slice(), "Err(Err)");
+    assert_eq!(s, "Err(Err)");
 }
 
 #[test]
diff --git a/src/libcoretest/tuple.rs b/src/libcoretest/tuple.rs
index be71e42ae9ad6561af273a2007dd1a218fd82f9a..c53d82de23c6c31a29102cee09fb90ca50ae6fb9 100644
--- a/src/libcoretest/tuple.rs
+++ b/src/libcoretest/tuple.rs
@@ -84,9 +84,9 @@ fn test_tuple_cmp() {
 #[test]
 fn test_show() {
     let s = format!("{}", (1i,));
-    assert_eq!(s.as_slice(), "(1,)");
+    assert_eq!(s, "(1,)");
     let s = format!("{}", (1i, true));
-    assert_eq!(s.as_slice(), "(1, true)");
+    assert_eq!(s, "(1, true)");
     let s = format!("{}", (1i, "hi", true));
-    assert_eq!(s.as_slice(), "(1, hi, true)");
+    assert_eq!(s, "(1, hi, true)");
 }