[review] add test for overriding partially unstable option

Author: tommilligan

src/config/mod.rs

@@ -406,6 +406,15 @@ mod test {
     #[allow(dead_code)]
     mod mock {
         use super::super::*;
+        use rustfmt_config_proc_macro::config_type;
+
+        #[config_type]
+        pub enum PartiallyUnstableOption {
+            V1,
+            V2,
+            #[unstable_variant]
+            V3,
+        }
 
         create_config! {
             // Options that are used by the generated functions
@@ -449,6 +458,8 @@ mod test {
             // Options that are used by the tests
             stable_option: bool, false, true, "A stable option";
             unstable_option: bool, false, false, "An unstable option";
+            partially_unstable_option: PartiallyUnstableOption, PartiallyUnstableOption::V1, true,
+                "A partially unstable option";
         }
     }
 
@@ -918,4 +929,42 @@ make_backup = false
             assert_eq!(config.single_line_if_else_max_width(), 100);
         }
     }
+
+    #[cfg(test)]
+    mod partially_unstable_option {
+        use super::mock::{Config, PartiallyUnstableOption};
+        use super::*;
+
+        #[test]
+        fn test_override_stable_value() {
+            let mut config = Config::default();
+            config.override_value("partially_unstable_option", "V2");
+            assert_eq!(
+                config.partially_unstable_option(),
+                PartiallyUnstableOption::V2
+            );
+        }
+
+        #[stable_only_test]
+        #[test]
+        fn test_override_unstable_value_on_stable() {
+            let mut config = Config::default();
+            config.override_value("partially_unstable_option", "V3");
+            assert_eq!(
+                config.partially_unstable_option(),
+                PartiallyUnstableOption::V1
+            );
+        }
+
+        #[nightly_only_test]
+        #[test]
+        fn test_override_unstable_value_on_nightly() {
+            let mut config = Config::default();
+            config.override_value("partially_unstable_option", "V3");
+            assert_eq!(
+                config.partially_unstable_option(),
+                PartiallyUnstableOption::V3
+            );
+        }
+    }
 }