tests: adds tests to protect against panics when using globals and calling App::get_matches_from_safe_borrow multiple times

tests/global_args.rs

@@ -0,0 +1,37 @@
+extern crate clap;
+extern crate regex;
+
+#[cfg(test)]
+mod tests {
+    include!("../clap-test.rs");
+    use clap::{App, Arg, SubCommand, ArgMatches};
+
+    fn get_app() -> App<'static, 'static> {
+        App::new("myprog")
+            .arg(Arg::with_name("GLOBAL_ARG")
+                .long("global-arg")
+                .help(
+                    "Specifies something needed by the subcommands",
+                )
+                .global(true)
+                .takes_value(true)
+                .default_value("default_value"))
+            .arg(Arg::with_name("GLOBAL_FLAG")
+                .long("global-flag")
+                .help(
+                    "Specifies something needed by the subcommands",
+                )
+                .multiple(true)
+                .global(true))
+            .subcommand(SubCommand::with_name("outer")
+                .subcommand(SubCommand::with_name("inner")))
+    }
+
+    #[test]
+    fn issue_1076() {
+        let mut app = get_app();
+        app.get_matches_from_safe_borrow(vec!["myprog"]);
+        app.get_matches_from_safe_borrow(vec!["myprog"]);
+        app.get_matches_from_safe_borrow(vec!["myprog"]);
+    }
+}