Merge main

.github/workflows/tests.yml

@@ -47,7 +47,7 @@ jobs:
       - name: Test
         run: cargo test --workspace
 
-  incremental-mutants:
+  pr-mutants:
     runs-on: ubuntu-latest
     if: github.event_name == 'pull_request'
     steps:

NEWS.md

@@ -8,9 +8,11 @@ A big internal refactor to allow mutations smaller than a whole function. Only o
 
 - New: Mutate `&&` to `||` and vice versa, and mutate both of them to `==` and `!=`.
 
+- Changed: If no mutants are generated then `cargo mutants` now exits successfully, showing a warning. (Previously it would exit with an error.) This works better with `--in-diff` in CI, where it's normal that some changes may not have any mutants.
+
 - Changed: Include column numbers in text listings of mutants and output to disambiguate smaller-than-function mutants, for example if there are several operators that can be changed on one line. This also applies to the names used for regex matching, so may break some regexps that match the entire line (sorry). The new option `--line-col=false` turns them both off in `--list` output.
 
-- Changed: Replaced the `function`, `line`, and `return_type` fields in the mutants json message with a `function` submessage (including the name and return type) and a `span` indicating the entire replaced region.
+- Changed: In the mutants.json format, replaced the `function`, `line`, and `return_type` fields with a `function` submessage (including the name and return type) and a `span` indicating the entire replaced region, to better handle smaller-than-function mutants. Also, the `function` includes the line-column span of the entire function.
 
 ## 23.11.2
 
@@ -24,8 +26,6 @@ A big internal refactor to allow mutations smaller than a whole function. Only o
 
 - Added: Accept `--manifest-path` as an alternative to `-d`, for consistency with other cargo commands.
 
-- Changed: The json mutants format now includes a `function` sub-message, which includes the function name and return type, rather than them being direct attributes of the mutant, to better accomodate smaller-than-function mutants. Also, the `function` includes the line-column span of the entire function.
-
 ## 23.11.1
 
 - New `--in-diff FILE` option tests only mutants that are in the diff from the

src/lab.rs

@@ -7,7 +7,7 @@ use std::sync::Mutex;
 use std::thread;
 use std::time::{Duration, Instant};
 
-use anyhow::{ensure, Result};
+use anyhow::Result;
 use itertools::Itertools;
 use tracing::warn;
 #[allow(unused)]
@@ -22,6 +22,9 @@ use crate::*;
 
 /// Run all possible mutation experiments.
 ///
+/// This is called after all filtering is complete, so all the mutants here will be tested
+/// or checked.
+///
 /// Before testing the mutants, the lab checks that the source tree passes its tests with no
 /// mutations applied.
 pub fn test_mutants(
@@ -43,7 +46,10 @@ pub fn test_mutants(
     }
     output_dir.write_mutants_list(&mutants)?;
     console.discovered_mutants(&mutants);
-    ensure!(!mutants.is_empty(), "No mutants found");
+    if mutants.is_empty() {
+        warn!("No mutants found under the active filters");
+        return Ok(LabOutcome::default());
+    }
     let all_packages = mutants.iter().map(|m| m.package()).unique().collect_vec();
     debug!(?all_packages);
 

src/visit.rs

@@ -46,7 +46,6 @@ pub fn walk_tree(
     options: &Options,
     console: &Console,
 ) -> Result<Discovered> {
-    // TODO: Lift up parsing the error expressions...
     let error_exprs = options
         .error_values
         .iter()

tests/cli/main.rs

@@ -666,15 +666,17 @@ fn integration_test_source_is_not_mutated() {
     check_text_list_output(tmp_src_dir.path(), "integration_test_source_is_not_mutated");
 }
 #[test]
-fn error_when_no_mutants_found() {
+fn warning_when_no_mutants_found() {
     let tmp_src_dir = copy_of_testdata("everything_skipped");
     run()
         .args(["mutants", "--check", "--no-times", "--no-shuffle"])
         .current_dir(tmp_src_dir.path())
         .assert()
-        .stderr(predicate::str::contains("Error: No mutants found"))
+        .stderr(predicate::str::contains(
+            "No mutants found under the active filters",
+        ))
         .stdout(predicate::str::contains("Found 0 mutants to test"))
-        .failure();
+        .success(); // It's arguable, but better if CI doesn't fail in this case.
 }
 
 #[test]