1 files changed, 66 insertions, 1 deletions
diff --git a/doc/tutorial/test.md b/doc/tutorial/test.md
index 636f65947a0..b7185c51085 100644
--- a/doc/tutorial/test.md
+++ b/doc/tutorial/test.md
@@ -1,3 +1,68 @@
 # Testing
 
-FIXME to be written
+The Rust language has a facility for testing built into the language.
+Tests can be interspersed with other code, and annotated with the
+`#[test]` attribute.
+
+    use std;
+    
+    fn twice(x: int) -> int { x + x }
+    
+    #[test]
+    fn test_twice() {
+        let i = -100;
+        while i < 100 {
+            assert twice(i) == 2 * i;
+            i += 1;
+        }
+    }
+
+When you compile the program normally, the `test_twice` function will
+not be used. To actually run the tests, compile with the `--test`
+flag:
+
+    > rustc --lib twice.rs
+    > ./twice
+    running 1 tests
+    test test_twice ... ok
+    result: ok. 1 passed; 0 failed; 0 ignored
+
+Or, if we change the file to fail, for example by replacing `x + x`
+with `x + 1`:
+
+    running 1 tests
+    test test_twice ... FAILED
+    failures:
+        test_twice
+    result: FAILED. 0 passed; 1 failed; 0 ignored
+
+You can pass a command-line argument to a program compiled with
+`--test` to run only the tests whose name matches the given string. If
+we had, for example, test functions `test_twice`, `test_once_1`, and
+`test_once_2`, running our program with `./twice test_once` would run
+the latter two, and running it with `./twice test_once_2` would run
+only the last.
+
+To indicate that a test is supposed to fail instead of pass, you can
+give it a `#[should_fail]` attribute.
+
+    use std;
+    
+    fn divide(a: float, b: float) -> float {
+        if b == 0f { fail; }
+        a / b
+    }
+    
+    #[test]
+    #[should_fail]
+    fn divide_by_zero() { divide(1f, 0f); }
+
+To disable a test completely, add an `#[ignore]` attribute. Running a
+test runner (the program compiled with `--test`) with an `--ignored`
+command-line flag will cause it to also run the tests labelled as
+ignored.
+
+A program compiled as a test runner will have the configuration flag
+`test` defined, so that you can add code that won't be included in a
+normal compile with the `#[cfg(test)]` attribute (see [conditional
+compilation](syntax.md#conditional)).