diff --git a/lib/spanned_sexp/src/lib.rs b/lib/spanned_sexp/src/lib.rs
index 5662aa8..0fabba1 100644
--- a/lib/spanned_sexp/src/lib.rs
+++ b/lib/spanned_sexp/src/lib.rs
@@ -32,13 +32,6 @@ pub enum Sexp {
   List(Vec<Sexp>),
 }
 
-#[test]
-fn sexp_size() {
-  // I just want to see when this changes, in the diff.
-  use std::mem;
-  assert_eq!(mem::size_of::<Sexp>(), mem::size_of::<isize>()*5);
-}
-
 /// The representation of an s-expression parse error.
 pub struct Error {
   /// The error message.
@@ -79,11 +72,6 @@ impl fmt::Debug for Error {
   }
 }
 
-#[test]
-fn show_an_error() {
-  assert_eq!(format!("{:?}", parse("(aaaa").unwrap_err()), "1:4: unexpected eof");
-}
-
 fn get_line_and_column(s: &str, pos: usize) -> (usize, usize) {
   let mut line: usize = 1;
   let mut col:  isize = -1;
@@ -98,20 +86,6 @@ fn get_line_and_column(s: &str, pos: usize) -> (usize, usize) {
   (line, cmp::max(col, 0) as usize)
 }
 
-#[test]
-fn line_and_col_test() {
-  let s = "0123456789\n0123456789\n\n6";
-  assert_eq!(get_line_and_column(s, 4), (1, 4));
-
-  assert_eq!(get_line_and_column(s, 10), (2, 0));
-  assert_eq!(get_line_and_column(s, 11), (2, 0));
-  assert_eq!(get_line_and_column(s, 15), (2, 4));
-
-  assert_eq!(get_line_and_column(s, 21), (3, 0));
-  assert_eq!(get_line_and_column(s, 22), (4, 0));
-  assert_eq!(get_line_and_column(s, 23), (4, 0));
-  assert_eq!(get_line_and_column(s, 500), (4, 0));
-}
 
 #[cold]
 fn err_impl(message: &'static str, s: &str, pos: &usize) -> Err {
@@ -375,43 +349,75 @@ impl fmt::Debug for Sexp {
   }
 }
 
-#[test]
-fn test_hello_world() {
-  assert_eq!(
-    parse("(hello -42\n\t  -4.0 \"world\") ; comment").unwrap(),
-    list(&[ atom_s("hello"), atom_i(-42), atom_f(-4.0), atom_s("world") ]));
-}
+#[cfg(test)]
+mod test {
+    use super::*;
 
-#[test]
-fn test_escaping() {
-  assert_eq!(
-    parse("(\"\\\"\\q\" \"1234\" 1234)").unwrap(),
-    list(&[ atom_s("\"\\q"), atom_s("1234"), atom_i(1234) ]));
-}
+    #[test]
+    fn test_hello_world() {
+        assert_eq!(
+            parse("(hello -42\n\t  -4.0 \"world\") ; comment").unwrap(),
+            list(&[ atom_s("hello"), atom_i(-42), atom_f(-4.0), atom_s("world") ]));
+    }
 
-#[test]
-fn test_pp() {
-  let s = "(hello world (what is (up) (4 6.4 you \"123\\\\ \\\"\")))";
-  let sexp = parse(s).unwrap();
-  assert_eq!(s, sexp.to_string());
-  assert_eq!(s, format!("{:?}", sexp));
-}
+    #[test]
+    fn test_escaping() {
+        assert_eq!(
+            parse("(\"\\\"\\q\" \"1234\" 1234)").unwrap(),
+            list(&[ atom_s("\"\\q"), atom_s("1234"), atom_i(1234) ]));
+    }
 
-#[test]
-fn test_tight_parens() {
-    let s = "(hello(world))";
-    let sexp = parse(s).unwrap();
-    assert_eq!(sexp, Sexp::List(vec![Sexp::Atom(Atom::S("hello".into())),
-                                     Sexp::List(vec![Sexp::Atom(Atom::S("world".into()))])]));
-    let s = "(this (has)tight(parens))";
-    let s2 = "( this ( has ) tight ( parens ) )";
-    assert_eq!(parse(s).unwrap(), parse(s2).unwrap());
-}
+    #[test]
+    fn test_pp() {
+        let s = "(hello world (what is (up) (4 6.4 you \"123\\\\ \\\"\")))";
+        let sexp = parse(s).unwrap();
+        assert_eq!(s, sexp.to_string());
+        assert_eq!(s, format!("{:?}", sexp));
+    }
+
+    #[test]
+    fn test_tight_parens() {
+        let s = "(hello(world))";
+        let sexp = parse(s).unwrap();
+        assert_eq!(sexp, Sexp::List(vec![Sexp::Atom(Atom::S("hello".into())),
+                                         Sexp::List(vec![Sexp::Atom(Atom::S("world".into()))])]));
+        let s = "(this (has)tight(parens))";
+        let s2 = "( this ( has ) tight ( parens ) )";
+        assert_eq!(parse(s).unwrap(), parse(s2).unwrap());
+    }
+
+    #[test]
+    fn test_space_in_atom() {
+        let sexp = list(&[ atom_s("hello world")]);
+        let sexp_as_string = sexp.to_string();
+        assert_eq!("(\"hello world\")", sexp_as_string);
+        assert_eq!(sexp, parse(&sexp_as_string).unwrap());
+    }
+
+    #[test]
+    fn show_an_error() {
+        assert_eq!(format!("{:?}", parse("(aaaa").unwrap_err()), "1:4: unexpected eof");
+    }
+
+    #[test]
+    fn line_and_col_test() {
+        let s = "0123456789\n0123456789\n\n6";
+        assert_eq!(get_line_and_column(s, 4), (1, 4));
+
+        assert_eq!(get_line_and_column(s, 10), (2, 0));
+        assert_eq!(get_line_and_column(s, 11), (2, 0));
+        assert_eq!(get_line_and_column(s, 15), (2, 4));
 
-#[test]
-fn test_space_in_atom() {
-  let sexp = list(&[ atom_s("hello world")]);
-  let sexp_as_string = sexp.to_string();
-  assert_eq!("(\"hello world\")", sexp_as_string);
-  assert_eq!(sexp, parse(&sexp_as_string).unwrap());
+        assert_eq!(get_line_and_column(s, 21), (3, 0));
+        assert_eq!(get_line_and_column(s, 22), (4, 0));
+        assert_eq!(get_line_and_column(s, 23), (4, 0));
+        assert_eq!(get_line_and_column(s, 500), (4, 0));
+    }
+
+    #[test]
+    fn sexp_size() {
+        // I just want to see when this changes, in the diff.
+        use std::mem;
+        assert_eq!(mem::size_of::<Sexp>(), mem::size_of::<isize>()*5);
+    }
 }