From eabc235f22f0701c26b0fa341609122f1781cf2e Mon Sep 17 00:00:00 2001
From: philipp <descpl@yahoo.de>
Date: Sat, 14 Oct 2023 20:11:46 +0200
Subject: [PATCH 1/3] check_specialized only needed within function

---
 tests/specializations.rs | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/tests/specializations.rs b/tests/specializations.rs
index 4fa6c33df..47c797291 100644
--- a/tests/specializations.rs
+++ b/tests/specializations.rs
@@ -17,23 +17,20 @@ where
     }
 }
 
-macro_rules! check_specialized {
-    ($src:expr, |$it:pat| $closure:expr) => {
-        let $it = $src.clone();
-        let v1 = $closure;
-
-        let $it = Unspecialized($src.clone());
-        let v2 = $closure;
-
-        assert_eq!(v1, v2);
-    };
-}
-
 fn test_specializations<IterItem, Iter>(it: &Iter)
 where
     IterItem: Eq + Debug + Clone,
     Iter: Iterator<Item = IterItem> + Clone,
 {
+    macro_rules! check_specialized {
+        ($src:expr, |$it:pat| $closure:expr) => {
+            let $it = $src.clone();
+            let v1 = $closure;
+            let $it = Unspecialized($src.clone());
+            let v2 = $closure;
+            assert_eq!(v1, v2);
+        };
+    }
     check_specialized!(it, |i| i.count());
     check_specialized!(it, |i| i.last());
     check_specialized!(it, |i| i.collect::<Vec<_>>());

From fbe6e32fc8d5d382f64540f03c5aab5eb931401e Mon Sep 17 00:00:00 2001
From: philipp <descpl@yahoo.de>
Date: Sat, 14 Oct 2023 20:20:00 +0200
Subject: [PATCH 2/3] Test specializations for next'ed iterators

---
 tests/specializations.rs | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/tests/specializations.rs b/tests/specializations.rs
index 47c797291..ba170c42c 100644
--- a/tests/specializations.rs
+++ b/tests/specializations.rs
@@ -24,12 +24,17 @@ where
 {
     macro_rules! check_specialized {
         ($src:expr, |$it:pat| $closure:expr) => {
-            let $it = $src.clone();
-            let v1 = $closure;
-            let $it = Unspecialized($src.clone());
-            let v2 = $closure;
-            assert_eq!(v1, v2);
-        };
+            // Many iterators special-case the first elements, so we test specializations for iterators that have already been advanced.
+            let mut src = $src.clone();
+            for _ in 0..5 {
+                let $it = src.clone();
+                let v1 = $closure;
+                let $it = Unspecialized(src.clone());
+                let v2 = $closure;
+                assert_eq!(v1, v2);
+                src.next();
+            }
+        }
     }
     check_specialized!(it, |i| i.count());
     check_specialized!(it, |i| i.last());

From 5d88dedc71bf112f6a02112fae5cfd2084d2de64 Mon Sep 17 00:00:00 2001
From: philipp <descpl@yahoo.de>
Date: Sat, 14 Oct 2023 20:27:43 +0200
Subject: [PATCH 3/3] Add TODO

process_results is as of now tested separately because the corresponding
iterator is not exposed nicely, and because it is not `Clone`.

However, the respective tests already diverged. Instead of fixing
process_results, we should strive to uniformly use test_specializations
for ProcessResults, too.
---
 tests/specializations.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/specializations.rs b/tests/specializations.rs
index ba170c42c..3f5e10685 100644
--- a/tests/specializations.rs
+++ b/tests/specializations.rs
@@ -129,6 +129,7 @@ quickcheck! {
 }
 
 quickcheck! {
+    // TODO Replace this function by a normal call to test_specializations
     fn process_results(v: Vec<Result<u8, u8>>) -> () {
         helper(v.iter().copied());
         helper(v.iter().copied().filter(Result::is_ok));