Add a syntax test to make sure they all work

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

tests/testsuite/build_script.rs

@@ -5168,3 +5168,39 @@ fn custom_build_closes_stdin() {
         .build();
     p.cargo("build").run();
 }
+
+#[cargo_test]
+fn test_both_two_semicolons_and_one_semicolon_syntax() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.0.1"
+                authors = []
+                build = "build.rs"
+            "#,
+        )
+        .file(
+            "src/main.rs",
+            r#"
+                const FOO: &'static str = env!("FOO");
+                const BAR: &'static str = env!("BAR");
+                fn main() {
+                    println!("{}", FOO);
+                    println!("{}", BAR);
+                }
+            "#,
+        )
+        .file(
+            "build.rs",
+            r#"fn main() {
+                println!("cargo::metadata=rustc-env=FOO=foo");
+                println!("cargo:rustc-env=BAR=bar");
+            }"#,
+        )
+        .build();
+    p.cargo("build -v").run();
+    p.cargo("run -v").with_stdout("foo\nbar\n").run();
+}