Merge pull request #801 from GuillaumeGomez/add-tests-readme

Add tests for rand_jitter README file

Author: dhardy

rand_jitter/README.md

@@ -38,15 +38,26 @@ recommend to run the much more stringent
 
 Use the following code using `timer_stats` to collect the data:
 
-```rust
+```rust,no_run
 use rand_jitter::JitterRng;
 
 use std::error::Error;
 use std::fs::File;
 use std::io::Write;
 
+fn get_nstime() -> u64 {
+    use std::time::{SystemTime, UNIX_EPOCH};
+
+    let dur = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
+    // The correct way to calculate the current time is
+    // `dur.as_secs() * 1_000_000_000 + dur.subsec_nanos() as u64`
+    // But this is faster, and the difference in terms of entropy is
+    // negligible (log2(10^9) == 29.9).
+    dur.as_secs() << 30 | dur.subsec_nanos() as u64
+}
+
 fn main() -> Result<(), Box<Error>> {
-    let mut rng = JitterRng::new()?;
+    let mut rng = JitterRng::new_with_timer(get_nstime);
 
     // 1_000_000 results are required for the
     // NIST SP 800-90B Entropy Estimation Suite

rand_jitter/src/lib.rs

@@ -63,6 +63,17 @@ extern crate libc;
 #[cfg(target_os = "windows")]
 extern crate winapi;
 
+// Coming from https://crates.io/crates/doc-comment
+#[cfg(test)]
+macro_rules! doc_comment {
+    ($x:expr) => {
+        #[doc = $x]
+        extern {}
+    };
+}
+
+#[cfg(test)]
+doc_comment!(include_str!("../README.md"));
 
 #[cfg(not(feature = "log"))]
 #[macro_use] mod dummy_log;