From 1962a5412d16f34c738e9f81bb5271da043a7505 Mon Sep 17 00:00:00 2001
From: Martin Pitt <martin@piware.de>
Date: Sun, 29 Aug 2021 16:25:47 +0200
Subject: [PATCH] concepts: require two Post approvals

---
 concepts/src/lib.rs  | 23 +++++++++++++++--------
 concepts/src/main.rs |  8 +++++++-
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/concepts/src/lib.rs b/concepts/src/lib.rs
index 923b80b..b0839ad 100644
--- a/concepts/src/lib.rs
+++ b/concepts/src/lib.rs
@@ -145,7 +145,7 @@ impl Post {
 
 trait State {
     fn request_review(&self) -> Box<dyn State>;
-    fn approve(&self) -> Box<dyn State>;
+    fn approve(&mut self) -> Box<dyn State>;
     fn reject(&self) -> Box<dyn State>;
 
     #[allow(unused_variables)]
@@ -157,10 +157,10 @@ trait State {
 struct Draft {}
 impl State for Draft {
     fn request_review(&self) -> Box<dyn State> {
-        Box::new(PendingReview {})
+        Box::new(PendingReview {acks: 0})
     }
 
-    fn approve(&self) -> Box<dyn State> {
+    fn approve(&mut self) -> Box<dyn State> {
         // don't change state
         Box::new(Self {})
     }
@@ -170,14 +170,21 @@ impl State for Draft {
     }
 }
 
-struct PendingReview {}
+struct PendingReview {
+    acks: u32,
+}
+
 impl State for PendingReview {
     fn request_review(&self) -> Box<dyn State> {
-        Box::new(Self {})
+        Box::new(Self {acks: self.acks})
     }
 
-    fn approve(&self) -> Box<dyn State> {
-        Box::new(Published {})
+    fn approve(&mut self) -> Box<dyn State> {
+        if self.acks >= 1 {
+            Box::new(Published {})
+        } else {
+            Box::new(Self {acks: self.acks + 1})
+        }
     }
 
     fn reject(&self) -> Box<dyn State> {
@@ -191,7 +198,7 @@ impl State for Published {
         Box::new(Self {})
     }
 
-    fn approve(&self) -> Box<dyn State> {
+    fn approve(&mut self) -> Box<dyn State> {
         Box::new(Published {})
     }
 
diff --git a/concepts/src/main.rs b/concepts/src/main.rs
index 3e9bbbd..2082621 100644
--- a/concepts/src/main.rs
+++ b/concepts/src/main.rs
@@ -262,7 +262,13 @@ fn test_dyn_traits() {
     post.request_review();
     assert_eq!("", post.content());
 
-    post.approve();
+    post.approve();  // first
+    assert_eq!("", post.content());
+
+    post.approve();  // second
+    assert_eq!(text, post.content());
+
+    post.reject();  // no-op
     assert_eq!(text, post.content());
 }
 
-- 
2.39.5