ci: Run most tests with miri

This PR additionally reduces the size of some heavy tests to
reduce their running time.

.github/workflows/ci.yml

@@ -54,6 +54,19 @@ jobs:
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test --all-features
 
+  miri:
+    runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly
+          components: miri
+      - uses: taiki-e/install-action@nextest
+      - run: cargo miri nextest run --all-features
+
   check-format:
     name: check format
     runs-on: ubuntu-latest

tests/quick.rs

@@ -2,7 +2,11 @@
 //! and adaptors.
 //!
 //! In particular we test the tedious size_hint and exact size correctness.
+//!
+//! **NOTE:** Due to performance limitations, these tests are not run with miri!
+//! They cannot be relied upon to discover soundness issues.
 
+#![cfg(not(miri))]
 #![allow(deprecated, unstable_name_collisions)]
 
 use itertools::free::{

tests/specializations.rs

@@ -1,3 +1,10 @@
+//! Test specializations of methods with default impls match the behavior of the
+//! default impls.
+//!
+//! **NOTE:** Due to performance limitations, these tests are not run with miri!
+//! They cannot be relied upon to discover soundness issues.
+
+#![cfg(not(miri))]
 #![allow(unstable_name_collisions)]
 
 use itertools::Itertools;

tests/test_std.rs

@@ -491,6 +491,7 @@ fn sorted_by() {
     it::assert_equal(v, vec![4, 3, 2, 1, 0]);
 }
 
+#[cfg(not(miri))]
 qc::quickcheck! {
     fn k_smallest_range(n: i64, m: u16, k: u16) -> () {
         // u16 is used to constrain k and m to 0..2¹⁶,
@@ -598,7 +599,9 @@ macro_rules! generic_test {
     };
 }
 
+#[cfg(not(miri))]
 generic_test!(k_smallest_sort, u8, u16, u32, u64, i8, i16, i32, i64);
+#[cfg(not(miri))]
 generic_test!(k_smallest_by_sort, u8, u16, u32, u64, i8, i16, i32, i64);
 
 #[test]
@@ -1055,8 +1058,8 @@ fn binomial(n: usize, k: usize) -> usize {
 
 #[test]
 fn combinations_range_count() {
-    for n in 0..=10 {
-        for k in 0..=10 {
+    for n in 0..=7 {
+        for k in 0..=7 {
             let len = binomial(n, k);
             let mut it = (0..n).combinations(k);
             assert_eq!(len, it.clone().count());
@@ -1077,7 +1080,7 @@ fn combinations_range_count() {
 
 #[test]
 fn combinations_inexact_size_hints() {
-    for k in 0..=10 {
+    for k in 0..=7 {
         let mut numbers = (0..18).filter(|i| i % 2 == 0); // 9 elements
         let mut it = numbers.clone().combinations(k);
         let real_n = numbers.clone().count();
@@ -1129,8 +1132,8 @@ fn permutations_zero() {
 
 #[test]
 fn permutations_range_count() {
-    for n in 0..=7 {
-        for k in 0..=7 {
+    for n in 0..=4 {
+        for k in 0..=4 {
             let len = if k <= n { (n - k + 1..=n).product() } else { 0 };
             let mut it = (0..n).permutations(k);
             assert_eq!(len, it.clone().count());
@@ -1162,6 +1165,7 @@ fn permutations_overflowed_size_hints() {
 }
 
 #[test]
+#[cfg(not(miri))]
 fn combinations_with_replacement() {
     // Pool smaller than n
     it::assert_equal((0..1).combinations_with_replacement(2), vec![vec![0, 0]]);
@@ -1190,8 +1194,8 @@ fn combinations_with_replacement() {
 
 #[test]
 fn combinations_with_replacement_range_count() {
-    for n in 0..=7 {
-        for k in 0..=7 {
+    for n in 0..=4 {
+        for k in 0..=4 {
             let len = binomial(usize::saturating_sub(n + k, 1), k);
             let mut it = (0..n).combinations_with_replacement(k);
             assert_eq!(len, it.clone().count());
@@ -1236,7 +1240,7 @@ fn powerset() {
     assert_eq!((0..8).powerset().count(), 1 << 8);
     assert_eq!((0..16).powerset().count(), 1 << 16);
 
-    for n in 0..=10 {
+    for n in 0..=4 {
         let mut it = (0..n).powerset();
         let len = 2_usize.pow(n);
         assert_eq!(len, it.clone().count());