Add assertions for required and default simultaneously

Add the suggested changes

Fix test issue_1050_num_vals_and_defaults

It used a required which isn't needed for the purpose of the test.

Add tests for the default+required assertions

Add test for positional args with long or short

src/build/app/debug_asserts.rs

@@ -219,14 +219,27 @@ pub(crate) fn assert_app(app: &App) {
             group.name,
         );
 
-        // Args listed inside groups should exist
         for arg in &group.args {
+            // Args listed inside groups should exist
             assert!(
                 app.args.args.iter().any(|x| x.id == *arg),
                 "Argument group '{}' contains non-existent argument '{:?}'",
                 group.name,
                 arg
-            )
+            );
+
+            // Required groups shouldn't have args with default values
+            if group.required {
+                assert!(
+                    app.args
+                        .args
+                        .iter()
+                        .any(|x| x.id == *arg && x.default_vals.is_empty()),
+                    "Argument group '{}' is required but contains argument '{:?}' which has a default value.",
+                    group.name,
+                    arg
+                )
+            }
         }
     }
 

src/build/arg/mod.rs

@@ -4397,6 +4397,14 @@ impl Arg<'_> {
                 self.name
             );
         }
+
+        if self.is_set(ArgSettings::Required) {
+            assert!(
+                self.default_vals.is_empty(),
+                "Argument '{}' is required and can't have a default value",
+                self.name
+            );
+        }
     }
 }
 

tests/default_vals.rs

@@ -493,7 +493,6 @@ fn issue_1050_num_vals_and_defaults() {
         .arg(
             Arg::new("exit-code")
                 .long("exit-code")
-                .required(true)
                 .takes_value(true)
                 .number_of_values(1)
                 .default_value("0"),
@@ -503,3 +502,26 @@ fn issue_1050_num_vals_and_defaults() {
     let m = res.unwrap();
     assert_eq!(m.value_of("exit-code"), Some("1"));
 }
+
+#[cfg(debug_assertions)]
+#[test]
+#[should_panic = "Argument group 'group' is required but contains argument 'arg' which has a default value."]
+fn required_groups_with_default_values() {
+    use clap::{App, Arg, ArgGroup};
+
+    let _ = App::new("test")
+        .arg(Arg::new("arg").default_value("value"))
+        .group(ArgGroup::new("group").args(&["arg"]).required(true))
+        .try_get_matches();
+}
+
+#[cfg(debug_assertions)]
+#[test]
+#[should_panic = "Argument 'arg' is required and can't have a default value"]
+fn required_args_with_default_values() {
+    use clap::{App, Arg};
+
+    let _ = App::new("test")
+        .arg(Arg::new("arg").required(true).default_value("value"))
+        .try_get_matches();
+}

tests/positionals.rs

@@ -268,3 +268,25 @@ fn last_positional_second_to_last_mult() {
         .try_get_matches_from(vec!["test", "tgt", "crp1", "crp2", "--", "arg"]);
     assert!(r.is_ok(), "{:?}", r.unwrap_err().kind);
 }
+
+#[cfg(debug_assertions)]
+#[test]
+#[should_panic = "Argument 'arg' is a positional argument and can't have short or long name versions"]
+fn positional_arg_with_long() {
+    use clap::{App, Arg};
+
+    let _ = App::new("test")
+        .arg(Arg::new("arg").index(1).long("arg"))
+        .try_get_matches();
+}
+
+#[cfg(debug_assertions)]
+#[test]
+#[should_panic = "Argument 'arg' is a positional argument and can't have short or long name versions"]
+fn positional_arg_with_short() {
+    use clap::{App, Arg};
+
+    let _ = App::new("test")
+        .arg(Arg::new("arg").index(1).short('a'))
+        .try_get_matches();
+}