Split the unit tests into several files.

src/lib.rs

@@ -1468,5 +1468,6 @@ impl<T: Counter, F: Counter> PartialEq<Histogram<F>> for Histogram<T>
 // TODO: timestamps and tags
 // TODO: textual output
 
+#[path = "tests/tests.rs"]
 #[cfg(test)]
 mod tests;

src/tests/helpers.rs

@@ -0,0 +1,8 @@
+use super::Histogram;
+
+#[cfg(test)]
+pub fn histo64(lowest_discernible_value: u64, highest_trackable_value: u64, num_significant_digits: u8)
+           -> Histogram<u64> {
+    Histogram::<u64>::new_with_bounds(lowest_discernible_value, highest_trackable_value,
+                                      num_significant_digits).unwrap()
+}

src/tests.rs → src/tests/init.rs

@@ -1,4 +1,4 @@
-use super::Histogram;
+use tests::helpers::histo64;
 
 #[test]
 fn init_fields_smallest_possible_array() {
@@ -250,23 +250,3 @@ fn init_fields_max_value_max_unit_magnitude_max_precision() {
 
     assert_eq!(64 - 62 - 1, h.leading_zero_count_base);
 }
-
-#[test]
-fn new_err_lowest_value_too_large_for_precision() {
-    let res = Histogram::<u64>::new_with_bounds(u64::max_value() / 2, u64::max_value(), 0);
-    assert_eq!("Cannot represent significant figures' worth of measurements beyond lowest value",
-               res.unwrap_err());
-}
-
-#[test]
-fn new_err_high_not_double_low() {
-    let res = Histogram::<u64>::new_with_bounds(10, 15, 0);
-    assert_eq!("highest trackable value must be >= 2 * lowest discernible value", res.unwrap_err());
-}
-
-#[cfg(test)]
-fn histo64(lowest_discernible_value: u64, highest_trackable_value: u64, num_significant_digits: u8)
-           -> Histogram<u64> {
-    Histogram::<u64>::new_with_bounds(lowest_discernible_value, highest_trackable_value,
-                                      num_significant_digits).unwrap()
-}

src/tests/tests.rs

@@ -0,0 +1,12 @@
+use super::Histogram;
+
+#[path = "helpers.rs"]
+mod helpers;
+#[path = "init.rs"]
+mod init;
+
+#[test]
+fn new_err_high_not_double_low() {
+    let res = Histogram::<u64>::new_with_bounds(10, 15, 0);
+    assert_eq!("highest trackable value must be >= 2 * lowest discernible value", res.unwrap_err());
+}