Fix parts of test suite not running

It disabled too much stuff through the use
of a non-existent cfg(feature="stable"). That now exists as
feature="rustc_is_stable", same with rustc_is_nightly.

Then, allows test_case_registration to become a default feature.
Essentially guards its use in cfg() with &= rustc_is_nightly, so stable
users do not have to --no-default-features.

Each test suite has instructions for running it at the top now.

Author: cormacrelf

src/lib.rs

@@ -137,21 +137,25 @@ pub mod __internal {
     pub use crate::runner::{
         check_test_runner, register, RegistrationNode, RegularShouldPanic, RegularTestDesc,
     };
-    #[cfg(not(feature = "test_case_registration"))]
+    // i.e. no TCR, use ctor instead
+    #[cfg(not(all(feature = "rustc_is_nightly", feature = "test_case_registration")))]
     pub use datatest_derive::{data_ctor_internal, files_ctor_internal};
-    #[cfg(feature = "test_case_registration")]
+    // i.e. use TCR
+    #[cfg(all(feature = "rustc_is_nightly", feature = "test_case_registration"))]
     pub use datatest_derive::{data_test_case_internal, files_test_case_internal};
 }
 
 pub use crate::runner::runner;
 
-#[cfg(not(feature = "test_case_registration"))]
+// i.e. no TCR, use ctor instead
+#[cfg(not(all(feature = "rustc_is_nightly", feature = "test_case_registration")))]
 pub use datatest_derive::{
     data_ctor_registration as data, files_ctor_registration as files,
     test_ctor_registration as test,
 };
 
-#[cfg(feature = "test_case_registration")]
+// i.e. use TCR
+#[cfg(all(feature = "rustc_is_nightly", feature = "test_case_registration"))]
 pub use datatest_derive::{
     data_test_case_registration as data, files_test_case_registration as files,
 };

tests/datatest.rs

@@ -1,7 +1,25 @@
-#![cfg(feature = "nightly")]
+//! cargo +nightly test                         # test_case_registration enabled
+//! cargo +nightly test --no-default-features   # no test_case_registration, uses ctor
+
+// self-testing config only:
+#![cfg(all(feature = "rustc_is_nightly"))]
+
 #![feature(custom_test_frameworks)]
 #![test_runner(datatest::runner)]
 
 // We want to share tests between "nightly" and "stable" suites. These have to be two different
 // suites as we set `harness = false` for the "stable" one.
 include!("tests/mod.rs");
+
+// Regular tests still work
+
+#[test]
+fn regular_test() {
+    println!("regular tests also work!");
+}
+
+#[test]
+fn regular_test_result() -> Result<(), Box<dyn std::error::Error>> {
+    println!("regular tests also work!");
+    Ok(())
+}

tests/datatest_stable.rs

@@ -1,19 +1,30 @@
-// We want to share tests between "nightly" and "stable" suites. These have to be two different
-// suites as we set `harness = false` for the "stable" one.
-include!("tests/mod.rs");
+//! cargo +stable test --features subvert_stable_guarantees
 
+// This test suite is configured with `harness = false` in Cargo.toml.
+// So we need to make sure it has a main function when testing nightly
+#[cfg(not(feature = "rustc_is_stable"))]
+fn main() {}
+// And uses the datatest harness when testing stable
+#[cfg(feature = "rustc_is_stable")]
 datatest::harness!();
 
-// Regular test have to use `datatest` variant of `#[test]` to work.
-use datatest::test;
+#[cfg(feature = "rustc_is_stable")]
+mod stable {
+    // Regular test have to use `datatest` variant of `#[test]` to work.
+    use datatest::test;
 
-#[test]
-fn regular_test() {
-    println!("regular tests also work!");
-}
+    // We want to share tests between "rustc_is_nightly" and "rustc_is_stable" suites. These have to be two different
+    // suites as we set `harness = false` for the "stable" one.
+    include!("tests/mod.rs");
+
+    #[test]
+    fn regular_test() {
+        println!("regular tests also work!");
+    }
 
-#[test]
-fn regular_test_result() -> Result<(), Box<dyn std::error::Error>> {
-    println!("regular tests also work!");
-    Ok(())
+    #[test]
+    fn regular_test_result() -> Result<(), Box<dyn std::error::Error>> {
+        println!("regular tests also work!");
+        Ok(())
+    }
 }

tests/datatest_stable_unsafe.rs

@@ -1,6 +1,7 @@
-//! Run with: `cargo +stable test --features unsafe_test_runner --test datatest_stable_unsafe`
+//! cargo +stable test --features subvert_stable_guarantees,unsafe_test_runner
 
-#[cfg(feature = "unsafe_test_runner")]
+#![cfg(feature = "rustc_is_stable")]
+#![cfg(feature = "unsafe_test_runner")]
 
 // We want to share tests between "nightly" and "stable" suites. These have to be two different
 // suites as we set `harness = false` for the "stable" one.

tests/tests/mod.rs

@@ -1,6 +1,3 @@
-#[cfg(feature = "stable")]
-use datatest::test;
-
 use serde::Deserialize;
 use std::fmt;
 use std::path::Path;

tests/unicode.rs

@@ -1,4 +1,4 @@
-#![cfg(feature = "nightly")]
+#![cfg(feature = "rustc_is_nightly")]
 #![feature(non_ascii_idents)]
 #![feature(custom_test_frameworks)]
 #![test_runner(datatest::runner)]