Add a test for compiletest rustc-env & unset-rustc-env directives

Author: tmiasko

src/test/ui/meta/auxiliary/env.rs

@@ -0,0 +1,9 @@
+// Check that aux builds can also use rustc-env, but environment is configured
+// separately from the main test case.
+//
+// rustc-env:COMPILETEST_BAR=bar
+
+pub fn test() {
+    assert_eq!(option_env!("COMPILETEST_FOO"), None);
+    assert_eq!(env!("COMPILETEST_BAR"), "bar");
+}

src/test/ui/meta/rustc-env.rs

@@ -0,0 +1,18 @@
+// Compiletest meta test checking that rustc-env and unset-rustc-env directives
+// can be used to configure environment for rustc.
+//
+// run-pass
+// aux-build:env.rs
+// rustc-env:COMPILETEST_FOO=foo
+//
+// An environment variable that is likely to be set, but should be safe to unset.
+// unset-rustc-env:PWD
+
+extern crate env;
+
+fn main() {
+    assert_eq!(env!("COMPILETEST_FOO"), "foo");
+    assert_eq!(option_env!("COMPILETEST_BAR"), None);
+    assert_eq!(option_env!("PWD"), None);
+    env::test();
+}