ci: Run most tests with miri

This PR additionally reduces the size of some heavy tests to
reduce their running time. We use nextest as our runner because it
runs tests in parallel. However, since nextest does not currenlty
run doc tests, we also run those separately.

.github/workflows/ci.yml

@@ -54,6 +54,21 @@ 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
+          cargo miri test --doc
+
   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());