tests: Test CPU-based RNG on all x86 targets

This allows us to verify the RDRAND implementation on Linux.

Signed-off-by: Joe Richey <[email protected]>

.travis.yml

@@ -122,11 +122,11 @@ jobs:
       script:
         # We test that getrandom builds for all targets
         - echo $STD_TARGETS | xargs -t -n1 cargo build --target
-        - echo $NO_STD_TARGETS | xargs -t -n1 cargo xbuild --target
+        - echo $NO_STD_TARGETS | xargs -t -n1 cargo xbuild --features=cpu --target
         # also test minimum dependency versions are usable
         - cargo generate-lockfile -Z minimal-versions
         - echo $STD_TARGETS | xargs -t -n1 cargo build --target
-        - echo $NO_STD_TARGETS | xargs -t -n1 cargo xbuild --target
+        - echo $NO_STD_TARGETS | xargs -t -n1 cargo xbuild --features=cpu --target
 
     # Trust cross-built/emulated targets. We must repeat all non-default values.
     - name: "Linux (MIPS, big-endian)"

src/lib.rs

@@ -217,3 +217,5 @@ pub fn getrandom(dest: &mut [u8]) -> Result<(), Error> {
 
 #[cfg(test)]
 mod test_common;
+#[cfg(test)]
+mod test_cpu;

src/test_cpu.rs

@@ -0,0 +1,8 @@
+// We only test the CPU-based RNG source on supported architectures.
+#![cfg(target_arch = "x86_64")]
+
+#[path = "rdrand.rs"]
+mod rdrand;
+use rdrand::getrandom_inner as getrandom;
+#[path = "test_common.rs"]
+mod test_common;