add external_crate test

fixtures/bitflags.rs

@@ -0,0 +1,22 @@
+#!/bin/true
+//# bitflags = "1.1.0"
+
+use bitflags::bitflags;
+
+bitflags! {
+    struct Flags: u32 {
+        const A = 0b00000001;
+        const B = 0b00000010;
+        const C = 0b00000100;
+        const ABC = Self::A.bits | Self::B.bits | Self::C.bits;
+    }
+}
+
+fn main() {
+    let e1 = Flags::A | Flags::C;
+    let e2 = Flags::B | Flags::C;
+    assert_eq!((e1 | e2), Flags::ABC); // union
+    assert_eq!((e1 & e2), Flags::C); // intersection
+    assert_eq!((e1 - e2), Flags::A); // set difference
+    assert_eq!(!e2, Flags::A); // set complement
+}

tests/integration_test.rs

@@ -199,3 +199,13 @@ fn program_args() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn external_crate() -> Result<()> {
+    let rt = TestRuntime::new()?;
+
+    let output = rt.run(&["fixtures/bitflags.rs"])?;
+    assert_eq!(output.status.code().unwrap(), 0);
+
+    Ok(())
+}