diff --git a/src/libserialize/hex.rs b/src/libserialize/hex.rs
index 8a7927e42c9..95d92f311ed 100644
--- a/src/libserialize/hex.rs
+++ b/src/libserialize/hex.rs
@@ -143,79 +143,4 @@ impl FromHex for str {
 }
 
 #[cfg(test)]
-mod tests {
-    extern crate test;
-    use test::Bencher;
-    use crate::hex::{FromHex, ToHex};
-
-    #[test]
-    pub fn test_to_hex() {
-        assert_eq!("foobar".as_bytes().to_hex(), "666f6f626172");
-    }
-
-    #[test]
-    pub fn test_from_hex_okay() {
-        assert_eq!("666f6f626172".from_hex().unwrap(),
-                   b"foobar");
-        assert_eq!("666F6F626172".from_hex().unwrap(),
-                   b"foobar");
-    }
-
-    #[test]
-    pub fn test_from_hex_odd_len() {
-        assert!("666".from_hex().is_err());
-        assert!("66 6".from_hex().is_err());
-    }
-
-    #[test]
-    pub fn test_from_hex_invalid_char() {
-        assert!("66y6".from_hex().is_err());
-    }
-
-    #[test]
-    pub fn test_from_hex_ignores_whitespace() {
-        assert_eq!("666f 6f6\r\n26172 ".from_hex().unwrap(),
-                   b"foobar");
-    }
-
-    #[test]
-    pub fn test_to_hex_all_bytes() {
-        for i in 0..256 {
-            assert_eq!([i as u8].to_hex(), format!("{:02x}", i as usize));
-        }
-    }
-
-    #[test]
-    pub fn test_from_hex_all_bytes() {
-        for i in 0..256 {
-            let ii: &[u8] = &[i as u8];
-            assert_eq!(format!("{:02x}", i as usize).from_hex()
-                                                   .unwrap(),
-                       ii);
-            assert_eq!(format!("{:02X}", i as usize).from_hex()
-                                                   .unwrap(),
-                       ii);
-        }
-    }
-
-    #[bench]
-    pub fn bench_to_hex(b: &mut Bencher) {
-        let s = "イロハニホヘト チリヌルヲ ワカヨタレソ ツネナラム \
-                 ウヰノオクヤマ ケフコエテ アサキユメミシ ヱヒモセスン";
-        b.iter(|| {
-            s.as_bytes().to_hex();
-        });
-        b.bytes = s.len() as u64;
-    }
-
-    #[bench]
-    pub fn bench_from_hex(b: &mut Bencher) {
-        let s = "イロハニホヘト チリヌルヲ ワカヨタレソ ツネナラム \
-                 ウヰノオクヤマ ケフコエテ アサキユメミシ ヱヒモセスン";
-        let sb = s.as_bytes().to_hex();
-        b.iter(|| {
-            sb.from_hex().unwrap();
-        });
-        b.bytes = sb.len() as u64;
-    }
-}
+mod tests;
diff --git a/src/libserialize/hex/tests.rs b/src/libserialize/hex/tests.rs
new file mode 100644
index 00000000000..471912c11d0
--- /dev/null
+++ b/src/libserialize/hex/tests.rs
@@ -0,0 +1,74 @@
+extern crate test;
+use test::Bencher;
+use crate::hex::{FromHex, ToHex};
+
+#[test]
+pub fn test_to_hex() {
+    assert_eq!("foobar".as_bytes().to_hex(), "666f6f626172");
+}
+
+#[test]
+pub fn test_from_hex_okay() {
+    assert_eq!("666f6f626172".from_hex().unwrap(),
+               b"foobar");
+    assert_eq!("666F6F626172".from_hex().unwrap(),
+               b"foobar");
+}
+
+#[test]
+pub fn test_from_hex_odd_len() {
+    assert!("666".from_hex().is_err());
+    assert!("66 6".from_hex().is_err());
+}
+
+#[test]
+pub fn test_from_hex_invalid_char() {
+    assert!("66y6".from_hex().is_err());
+}
+
+#[test]
+pub fn test_from_hex_ignores_whitespace() {
+    assert_eq!("666f 6f6\r\n26172 ".from_hex().unwrap(),
+               b"foobar");
+}
+
+#[test]
+pub fn test_to_hex_all_bytes() {
+    for i in 0..256 {
+        assert_eq!([i as u8].to_hex(), format!("{:02x}", i as usize));
+    }
+}
+
+#[test]
+pub fn test_from_hex_all_bytes() {
+    for i in 0..256 {
+        let ii: &[u8] = &[i as u8];
+        assert_eq!(format!("{:02x}", i as usize).from_hex()
+                                               .unwrap(),
+                   ii);
+        assert_eq!(format!("{:02X}", i as usize).from_hex()
+                                               .unwrap(),
+                   ii);
+    }
+}
+
+#[bench]
+pub fn bench_to_hex(b: &mut Bencher) {
+    let s = "イロハニホヘト チリヌルヲ ワカヨタレソ ツネナラム \
+             ウヰノオクヤマ ケフコエテ アサキユメミシ ヱヒモセスン";
+    b.iter(|| {
+        s.as_bytes().to_hex();
+    });
+    b.bytes = s.len() as u64;
+}
+
+#[bench]
+pub fn bench_from_hex(b: &mut Bencher) {
+    let s = "イロハニホヘト チリヌルヲ ワカヨタレソ ツネナラム \
+             ウヰノオクヤマ ケフコエテ アサキユメミシ ヱヒモセスン";
+    let sb = s.as_bytes().to_hex();
+    b.iter(|| {
+        sb.from_hex().unwrap();
+    });
+    b.bytes = sb.len() as u64;
+}
diff --git a/src/libserialize/json.rs b/src/libserialize/json.rs
index a4fd2884512..8f926e6dd29 100644
--- a/src/libserialize/json.rs
+++ b/src/libserialize/json.rs
@@ -2582,139 +2582,4 @@ impl FromStr for Json {
 }
 
 #[cfg(test)]
-mod tests {
-    // Benchmarks and tests that require private items
-
-    extern crate test;
-    use test::Bencher;
-    use super::{from_str, Parser, StackElement, Stack};
-    use std::string;
-
-    #[test]
-    fn test_stack() {
-        let mut stack = Stack::new();
-
-        assert!(stack.is_empty());
-        assert!(stack.is_empty());
-        assert!(!stack.last_is_index());
-
-        stack.push_index(0);
-        stack.bump_index();
-
-        assert!(stack.len() == 1);
-        assert!(stack.is_equal_to(&[StackElement::Index(1)]));
-        assert!(stack.starts_with(&[StackElement::Index(1)]));
-        assert!(stack.ends_with(&[StackElement::Index(1)]));
-        assert!(stack.last_is_index());
-        assert!(stack.get(0) == StackElement::Index(1));
-
-        stack.push_key("foo".to_string());
-
-        assert!(stack.len() == 2);
-        assert!(stack.is_equal_to(&[StackElement::Index(1), StackElement::Key("foo")]));
-        assert!(stack.starts_with(&[StackElement::Index(1), StackElement::Key("foo")]));
-        assert!(stack.starts_with(&[StackElement::Index(1)]));
-        assert!(stack.ends_with(&[StackElement::Index(1), StackElement::Key("foo")]));
-        assert!(stack.ends_with(&[StackElement::Key("foo")]));
-        assert!(!stack.last_is_index());
-        assert!(stack.get(0) == StackElement::Index(1));
-        assert!(stack.get(1) == StackElement::Key("foo"));
-
-        stack.push_key("bar".to_string());
-
-        assert!(stack.len() == 3);
-        assert!(stack.is_equal_to(&[StackElement::Index(1),
-                                    StackElement::Key("foo"),
-                                    StackElement::Key("bar")]));
-        assert!(stack.starts_with(&[StackElement::Index(1)]));
-        assert!(stack.starts_with(&[StackElement::Index(1), StackElement::Key("foo")]));
-        assert!(stack.starts_with(&[StackElement::Index(1),
-                                    StackElement::Key("foo"),
-                                    StackElement::Key("bar")]));
-        assert!(stack.ends_with(&[StackElement::Key("bar")]));
-        assert!(stack.ends_with(&[StackElement::Key("foo"), StackElement::Key("bar")]));
-        assert!(stack.ends_with(&[StackElement::Index(1),
-                                  StackElement::Key("foo"),
-                                  StackElement::Key("bar")]));
-        assert!(!stack.last_is_index());
-        assert!(stack.get(0) == StackElement::Index(1));
-        assert!(stack.get(1) == StackElement::Key("foo"));
-        assert!(stack.get(2) == StackElement::Key("bar"));
-
-        stack.pop();
-
-        assert!(stack.len() == 2);
-        assert!(stack.is_equal_to(&[StackElement::Index(1), StackElement::Key("foo")]));
-        assert!(stack.starts_with(&[StackElement::Index(1), StackElement::Key("foo")]));
-        assert!(stack.starts_with(&[StackElement::Index(1)]));
-        assert!(stack.ends_with(&[StackElement::Index(1), StackElement::Key("foo")]));
-        assert!(stack.ends_with(&[StackElement::Key("foo")]));
-        assert!(!stack.last_is_index());
-        assert!(stack.get(0) == StackElement::Index(1));
-        assert!(stack.get(1) == StackElement::Key("foo"));
-    }
-
-    #[bench]
-    fn bench_streaming_small(b: &mut Bencher) {
-        b.iter( || {
-            let mut parser = Parser::new(
-                r#"{
-                    "a": 1.0,
-                    "b": [
-                        true,
-                        "foo\nbar",
-                        { "c": {"d": null} }
-                    ]
-                }"#.chars()
-            );
-            loop {
-                match parser.next() {
-                    None => return,
-                    _ => {}
-                }
-            }
-        });
-    }
-    #[bench]
-    fn bench_small(b: &mut Bencher) {
-        b.iter( || {
-            let _ = from_str(r#"{
-                "a": 1.0,
-                "b": [
-                    true,
-                    "foo\nbar",
-                    { "c": {"d": null} }
-                ]
-            }"#);
-        });
-    }
-
-    fn big_json() -> string::String {
-        let mut src = "[\n".to_string();
-        for _ in 0..500 {
-            src.push_str(r#"{ "a": true, "b": null, "c":3.1415, "d": "Hello world", "e": \
-                            [1,2,3]},"#);
-        }
-        src.push_str("{}]");
-        return src;
-    }
-
-    #[bench]
-    fn bench_streaming_large(b: &mut Bencher) {
-        let src = big_json();
-        b.iter( || {
-            let mut parser = Parser::new(src.chars());
-            loop {
-                match parser.next() {
-                    None => return,
-                    _ => {}
-                }
-            }
-        });
-    }
-    #[bench]
-    fn bench_large(b: &mut Bencher) {
-        let src = big_json();
-        b.iter( || { let _ = from_str(&src); });
-    }
-}
+mod tests;
diff --git a/src/libserialize/json/tests.rs b/src/libserialize/json/tests.rs
new file mode 100644
index 00000000000..a16b8bdd787
--- /dev/null
+++ b/src/libserialize/json/tests.rs
@@ -0,0 +1,134 @@
+// Benchmarks and tests that require private items
+
+extern crate test;
+use test::Bencher;
+use super::{from_str, Parser, StackElement, Stack};
+use std::string;
+
+#[test]
+fn test_stack() {
+    let mut stack = Stack::new();
+
+    assert!(stack.is_empty());
+    assert!(stack.is_empty());
+    assert!(!stack.last_is_index());
+
+    stack.push_index(0);
+    stack.bump_index();
+
+    assert!(stack.len() == 1);
+    assert!(stack.is_equal_to(&[StackElement::Index(1)]));
+    assert!(stack.starts_with(&[StackElement::Index(1)]));
+    assert!(stack.ends_with(&[StackElement::Index(1)]));
+    assert!(stack.last_is_index());
+    assert!(stack.get(0) == StackElement::Index(1));
+
+    stack.push_key("foo".to_string());
+
+    assert!(stack.len() == 2);
+    assert!(stack.is_equal_to(&[StackElement::Index(1), StackElement::Key("foo")]));
+    assert!(stack.starts_with(&[StackElement::Index(1), StackElement::Key("foo")]));
+    assert!(stack.starts_with(&[StackElement::Index(1)]));
+    assert!(stack.ends_with(&[StackElement::Index(1), StackElement::Key("foo")]));
+    assert!(stack.ends_with(&[StackElement::Key("foo")]));
+    assert!(!stack.last_is_index());
+    assert!(stack.get(0) == StackElement::Index(1));
+    assert!(stack.get(1) == StackElement::Key("foo"));
+
+    stack.push_key("bar".to_string());
+
+    assert!(stack.len() == 3);
+    assert!(stack.is_equal_to(&[StackElement::Index(1),
+                                StackElement::Key("foo"),
+                                StackElement::Key("bar")]));
+    assert!(stack.starts_with(&[StackElement::Index(1)]));
+    assert!(stack.starts_with(&[StackElement::Index(1), StackElement::Key("foo")]));
+    assert!(stack.starts_with(&[StackElement::Index(1),
+                                StackElement::Key("foo"),
+                                StackElement::Key("bar")]));
+    assert!(stack.ends_with(&[StackElement::Key("bar")]));
+    assert!(stack.ends_with(&[StackElement::Key("foo"), StackElement::Key("bar")]));
+    assert!(stack.ends_with(&[StackElement::Index(1),
+                              StackElement::Key("foo"),
+                              StackElement::Key("bar")]));
+    assert!(!stack.last_is_index());
+    assert!(stack.get(0) == StackElement::Index(1));
+    assert!(stack.get(1) == StackElement::Key("foo"));
+    assert!(stack.get(2) == StackElement::Key("bar"));
+
+    stack.pop();
+
+    assert!(stack.len() == 2);
+    assert!(stack.is_equal_to(&[StackElement::Index(1), StackElement::Key("foo")]));
+    assert!(stack.starts_with(&[StackElement::Index(1), StackElement::Key("foo")]));
+    assert!(stack.starts_with(&[StackElement::Index(1)]));
+    assert!(stack.ends_with(&[StackElement::Index(1), StackElement::Key("foo")]));
+    assert!(stack.ends_with(&[StackElement::Key("foo")]));
+    assert!(!stack.last_is_index());
+    assert!(stack.get(0) == StackElement::Index(1));
+    assert!(stack.get(1) == StackElement::Key("foo"));
+}
+
+#[bench]
+fn bench_streaming_small(b: &mut Bencher) {
+    b.iter( || {
+        let mut parser = Parser::new(
+            r#"{
+                "a": 1.0,
+                "b": [
+                    true,
+                    "foo\nbar",
+                    { "c": {"d": null} }
+                ]
+            }"#.chars()
+        );
+        loop {
+            match parser.next() {
+                None => return,
+                _ => {}
+            }
+        }
+    });
+}
+#[bench]
+fn bench_small(b: &mut Bencher) {
+    b.iter( || {
+        let _ = from_str(r#"{
+            "a": 1.0,
+            "b": [
+                true,
+                "foo\nbar",
+                { "c": {"d": null} }
+            ]
+        }"#);
+    });
+}
+
+fn big_json() -> string::String {
+    let mut src = "[\n".to_string();
+    for _ in 0..500 {
+        src.push_str(r#"{ "a": true, "b": null, "c":3.1415, "d": "Hello world", "e": \
+                        [1,2,3]},"#);
+    }
+    src.push_str("{}]");
+    return src;
+}
+
+#[bench]
+fn bench_streaming_large(b: &mut Bencher) {
+    let src = big_json();
+    b.iter( || {
+        let mut parser = Parser::new(src.chars());
+        loop {
+            match parser.next() {
+                None => return,
+                _ => {}
+            }
+        }
+    });
+}
+#[bench]
+fn bench_large(b: &mut Bencher) {
+    let src = big_json();
+    b.iter( || { let _ = from_str(&src); });
+}