5 files changed, 33 insertions, 27 deletions
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index 4b3fefcd4de..8e0581b41ef 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -80,6 +80,9 @@ extern crate libc;
 // librustc_driver and libtest.
 extern crate test as _;
 
+#[cfg(test)]
+mod tests;
+
 #[macro_use]
 mod macros;
 
@@ -138,18 +141,5 @@ pub mod util {
 // Allows macros to refer to this crate as `::rustc`
 extern crate self as rustc;
 
-// FIXME(#27438): right now the unit tests of librustc don't refer to any actual
-//                functions generated in librustc_data_structures (all
-//                references are through generic functions), but statics are
-//                referenced from time to time. Due to this bug we won't
-//                actually correctly link in the statics unless we also
-//                reference a function, so be sure to reference a dummy
-//                function.
-#[test]
-fn noop() {
-    rustc_data_structures::__noop_fix_for_27438();
-}
-
-
 // Build the diagnostics array at the end so that the metadata includes error use sites.
 __build_diagnostic_array! { librustc, DIAGNOSTICS }
diff --git a/src/librustc/tests.rs b/src/librustc/tests.rs
new file mode 100644
index 00000000000..cf3ea2ffa93
--- /dev/null
+++ b/src/librustc/tests.rs
@@ -0,0 +1,13 @@
+use super::*;
+
+// FIXME(#27438): right now the unit tests of librustc don't refer to any actual
+//                functions generated in librustc_data_structures (all
+//                references are through generic functions), but statics are
+//                referenced from time to time. Due to this bug we won't
+//                actually correctly link in the statics unless we also
+//                reference a function, so be sure to reference a dummy
+//                function.
+#[test]
+fn noop() {
+    rustc_data_structures::__noop_fix_for_27438();
+}
diff --git a/src/librustc/util/common.rs b/src/librustc/util/common.rs
index 8e7936dae09..7118d05204c 100644
--- a/src/librustc/util/common.rs
+++ b/src/librustc/util/common.rs
@@ -18,6 +18,9 @@ use crate::dep_graph::{DepNode};
 use lazy_static;
 use crate::session::Session;
 
+#[cfg(test)]
+mod tests;
+
 // The name of the associated type for `Fn` return types.
 pub const FN_OUTPUT_NAME: Symbol = sym::Output;
 
@@ -349,16 +352,3 @@ impl<K, V> MemoizationMap for RefCell<FxHashMap<K,V>>
         }
     }
 }
-
-#[test]
-fn test_to_readable_str() {
-    assert_eq!("0", to_readable_str(0));
-    assert_eq!("1", to_readable_str(1));
-    assert_eq!("99", to_readable_str(99));
-    assert_eq!("999", to_readable_str(999));
-    assert_eq!("1_000", to_readable_str(1_000));
-    assert_eq!("1_001", to_readable_str(1_001));
-    assert_eq!("999_999", to_readable_str(999_999));
-    assert_eq!("1_000_000", to_readable_str(1_000_000));
-    assert_eq!("1_234_567", to_readable_str(1_234_567));
-}
diff --git a/src/librustc/util/common/tests.rs b/src/librustc/util/common/tests.rs
new file mode 100644
index 00000000000..9a9fb203c62
--- /dev/null
+++ b/src/librustc/util/common/tests.rs
@@ -0,0 +1,14 @@
+use super::*;
+
+#[test]
+fn test_to_readable_str() {
+    assert_eq!("0", to_readable_str(0));
+    assert_eq!("1", to_readable_str(1));
+    assert_eq!("99", to_readable_str(99));
+    assert_eq!("999", to_readable_str(999));
+    assert_eq!("1_000", to_readable_str(1_000));
+    assert_eq!("1_001", to_readable_str(1_001));
+    assert_eq!("999_999", to_readable_str(999_999));
+    assert_eq!("1_000_000", to_readable_str(1_000_000));
+    assert_eq!("1_234_567", to_readable_str(1_234_567));
+}
diff --git a/src/tools/tidy/src/unit_tests.rs b/src/tools/tidy/src/unit_tests.rs
index 79ccc11a69a..d7d47721170 100644
--- a/src/tools/tidy/src/unit_tests.rs
+++ b/src/tools/tidy/src/unit_tests.rs
@@ -27,7 +27,6 @@ pub fn check(root_path: &Path, bad: &mut bool) {
     };
     let fixme = [
         "liballoc",
-        "librustc",
         "librustc_data_structures",
         "librustdoc",
         "libstd",