Simplify known external tests (#5219)

* Simplify known external tests

* Cargo fmt

examples/test_hello.rs

@@ -1,6 +0,0 @@
-/// This function is only meant to be used as part of the test suite
-/// as a simple, cross-platform executable with known output.
-
-fn main() {
-    println!("test-hello");
-}

src/tests/test_known_external.rs

@@ -1,17 +1,17 @@
-use crate::tests::{fail_test, run_test, TestResult};
+use crate::tests::{fail_test, run_test_contains, TestResult};
+
+// cargo version prints a string of the form:
+// cargo 1.60.0 (d1fd9fe2c 2022-03-01)
 
 #[test]
 fn known_external_runs() -> TestResult {
-    run_test(
+    run_test_contains(r#"extern "cargo version" []; cargo version"#, "cargo")
-        r#"extern "cargo run" [-q, --example: string, ...args]; cargo run -q --example test_hello"#,
-        "test-hello",
-    )
 }
 
 #[test]
 fn known_external_unknown_flag() -> TestResult {
     fail_test(
-        r#"extern "cargo run" [-q, --example: string, ...args]; cargo run -d"#,
+        r#"extern "cargo version" []; cargo version --no-such-flag"#,
         "command doesn't have flag",
     )
 }
@@ -19,17 +19,17 @@ fn known_external_unknown_flag() -> TestResult {
 /// GitHub issues #5179, #4618
 #[test]
 fn known_external_alias() -> TestResult {
-    run_test(
+    run_test_contains(
-        r#"extern "cargo run" [-q, --example: string, ...args]; alias cr = cargo run; cr -q --example test_hello"#,
+        r#"extern "cargo version" []; alias cv = cargo version; cv"#,
-        "test-hello",
+        "cargo",
     )
 }
 
 /// GitHub issues #5179, #4618
 #[test]
 fn known_external_subcommand_alias() -> TestResult {
-    run_test(
+    run_test_contains(
-        r#"extern "cargo run" [-q, --example: string, ...args]; alias c = cargo; c run -q --example test_hello"#,
+        r#"extern "cargo version" []; alias c = cargo; c version"#,
-        "test-hello",
+        "cargo",
     )
 }