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Merged
sourcefrog merged 2 commits into from
Dec 10, 2025
Merged

Include mutant name in JSON output (issue #480) #573

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ae324ef
Include mutant name in JSON output (issue #480)
0xLoopTheory Dec 7, 2025
1e4f5ae
Refactor mutant name computation into constructor
0xLoopTheory Dec 9, 2025
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35 changes: 35 additions & 0 deletions src/mutant.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,12 @@ pub enum MutationTarget {
/// A mutation applied to source code.
#[derive(Clone, Eq, PartialEq, Debug)]
pub struct Mutant {
/// A precomputed human-readable name for this mutant, including the file,
/// location, and change description.
///
/// This is used in CLI output, filtering, and JSON.
pub name: String,

/// Which file is being mutated.
pub source_file: SourceFile,

Expand Down Expand Up @@ -103,6 +109,34 @@ pub struct Function {
}

impl Mutant {
/// Construct a mutant discovered while walking source code.
///
/// This initializes all fields and precomputes the human-readable `name`
/// (including file path, line/column, and change description) for use in
/// CLI output, filtering, and JSON.
pub(crate) fn new_discovered(
source_file: SourceFile,
function: Option<Arc<Function>>,
span: Span,
short_replaced: Option<String>,
replacement: String,
genre: Genre,
target: Option<MutationTarget>,
) -> Self {
let mut mutant = Mutant {
name: String::new(),
source_file,
function,
span,
short_replaced,
replacement,
genre,
target,
};
mutant.name = mutant.name(true);
mutant
}

/// Return text of the whole file with the mutation applied.
pub fn mutated_code(&self) -> String {
self.span.replace(
Expand Down Expand Up @@ -293,6 +327,7 @@ impl Serialize for Mutant {
{
// custom serialize to omit inessential info
let mut ss = serializer.serialize_struct("Mutant", 7)?;
ss.serialize_field("name", &self.name)?;
ss.serialize_field("package", &self.source_file.package.name)?;
ss.serialize_field("file", &self.source_file.tree_relative_slashes())?;
ss.serialize_field("function", &self.function.as_ref().map(Arc::as_ref))?;
Expand Down
53 changes: 27 additions & 26 deletions src/visit.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,9 @@ pub struct Discovered {
impl Discovered {
pub(crate) fn remove_previously_caught(&mut self, previously_caught: &[String]) {
self.mutants.retain(|m| {
let name = m.name(true);
let c = previously_caught.contains(&name);
let c = previously_caught.contains(&m.name);
if c {
trace!(?name, "skip previously caught mutant");
trace!(name = %m.name, "skip previously caught mutant");
}
!c
});
Expand Down Expand Up @@ -75,6 +74,7 @@ pub fn walk_tree(
mutants.append(&mut package_mutants);
files.append(&mut package_files);
}

progress.finish();
Ok(Discovered { mutants, files })
}
Expand Down Expand Up @@ -318,15 +318,16 @@ impl DiscoveryVisitor<'_> {

/// Record that we generated some mutants.
fn collect_mutant(&mut self, span: Span, replacement: &TokenStream, genre: Genre) {
self.mutants.push(Mutant {
source_file: self.source_file.clone(),
function: self.fn_stack.last().cloned(),
let mutant = Mutant::new_discovered(
self.source_file.clone(),
self.fn_stack.last().cloned(),
span,
short_replaced: None,
replacement: replacement.to_pretty_string(),
None,
replacement.to_pretty_string(),
genre,
target: None,
});
None,
);
self.mutants.push(mutant);
}

fn collect_fn_mutants(&mut self, sig: &Signature, block: &Block) {
Expand Down Expand Up @@ -656,15 +657,15 @@ impl<'ast> Visit<'ast> for DiscoveryVisitor<'_> {
continue;
}
let short_replaced = Some(arm.pat.to_pretty_string());
let mutant = Mutant {
source_file: self.source_file.clone(),
function: self.fn_stack.last().cloned(),
span: arm.span().into(),
let mutant = Mutant::new_discovered(
self.source_file.clone(),
self.fn_stack.last().cloned(),
arm.span().into(),
short_replaced,
replacement: String::new(),
genre: Genre::MatchArm,
target: None,
};
String::new(),
Genre::MatchArm,
None,
);
self.mutants.push(mutant);
}
} else {
Expand Down Expand Up @@ -722,18 +723,18 @@ impl<'ast> Visit<'ast> for DiscoveryVisitor<'_> {
// No comma, just the field
field.span().into()
};
let mutant = Mutant {
source_file: self.source_file.clone(),
function: self.fn_stack.last().cloned(),
let mutant = Mutant::new_discovered(
self.source_file.clone(),
self.fn_stack.last().cloned(),
span,
short_replaced: None,
replacement: String::new(),
genre: Genre::StructField,
target: Some(MutationTarget::StructLiteralField {
None,
String::new(),
Genre::StructField,
Some(MutationTarget::StructLiteralField {
field_name: field_name_str,
struct_name: struct_name.clone(),
}),
};
);
self.mutants.push(mutant);
}
}
Expand Down
5 changes: 5 additions & 0 deletions tests/snapshots/main__mutants.json.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ expression: mutants_json
---
[
{
"name": "src/bin/factorial.rs:2:5: replace main with ()",
"package": "cargo-mutants-testdata-factorial",
"file": "src/bin/factorial.rs",
"function": {
Expand Down Expand Up @@ -34,6 +35,7 @@ expression: mutants_json
"genre": "FnValue"
},
{
"name": "src/bin/factorial.rs:8:5: replace factorial -> u32 with 0",
"package": "cargo-mutants-testdata-factorial",
"file": "src/bin/factorial.rs",
"function": {
Expand Down Expand Up @@ -64,6 +66,7 @@ expression: mutants_json
"genre": "FnValue"
},
{
"name": "src/bin/factorial.rs:8:5: replace factorial -> u32 with 1",
"package": "cargo-mutants-testdata-factorial",
"file": "src/bin/factorial.rs",
"function": {
Expand Down Expand Up @@ -94,6 +97,7 @@ expression: mutants_json
"genre": "FnValue"
},
{
"name": "src/bin/factorial.rs:10:11: replace *= with += in factorial",
"package": "cargo-mutants-testdata-factorial",
"file": "src/bin/factorial.rs",
"function": {
Expand Down Expand Up @@ -124,6 +128,7 @@ expression: mutants_json
"genre": "BinaryOperator"
},
{
"name": "src/bin/factorial.rs:10:11: replace *= with /= in factorial",
"package": "cargo-mutants-testdata-factorial",
"file": "src/bin/factorial.rs",
"function": {
Expand Down
4 changes: 4 additions & 0 deletions tests/util/snapshots/main__util__list_mutants_in_cfg_attr_test_skip_json.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "FnValue",
"name": "src/lib.rs:18:5: replace double -> usize with 0",
"package": "cargo-mutants-testdata-cfg-attr-test-skip",
"replacement": "0",
"span": {
Expand Down Expand Up @@ -50,6 +51,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "FnValue",
"name": "src/lib.rs:18:5: replace double -> usize with 1",
"package": "cargo-mutants-testdata-cfg-attr-test-skip",
"replacement": "1",
"span": {
Expand Down Expand Up @@ -80,6 +82,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "BinaryOperator",
"name": "src/lib.rs:18:7: replace * with + in double",
"package": "cargo-mutants-testdata-cfg-attr-test-skip",
"replacement": "+",
"span": {
Expand Down Expand Up @@ -110,6 +113,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "BinaryOperator",
"name": "src/lib.rs:18:7: replace * with / in double",
"package": "cargo-mutants-testdata-cfg-attr-test-skip",
"replacement": "/",
"span": {
Expand Down
5 changes: 5 additions & 0 deletions tests/util/snapshots/main__util__list_mutants_in_factorial_json.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "FnValue",
"name": "src/bin/factorial.rs:2:5: replace main with ()",
"package": "cargo-mutants-testdata-factorial",
"replacement": "()",
"span": {
Expand Down Expand Up @@ -50,6 +51,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "FnValue",
"name": "src/bin/factorial.rs:8:5: replace factorial -> u32 with 0",
"package": "cargo-mutants-testdata-factorial",
"replacement": "0",
"span": {
Expand Down Expand Up @@ -80,6 +82,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "FnValue",
"name": "src/bin/factorial.rs:8:5: replace factorial -> u32 with 1",
"package": "cargo-mutants-testdata-factorial",
"replacement": "1",
"span": {
Expand Down Expand Up @@ -110,6 +113,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "BinaryOperator",
"name": "src/bin/factorial.rs:10:11: replace *= with += in factorial",
"package": "cargo-mutants-testdata-factorial",
"replacement": "+=",
"span": {
Expand Down Expand Up @@ -140,6 +144,7 @@ expression: "String::from_utf8_lossy(&output.stdout)"
}
},
"genre": "BinaryOperator",
"name": "src/bin/factorial.rs:10:11: replace *= with /= in factorial",
"package": "cargo-mutants-testdata-factorial",
"replacement": "/=",
"span": {
Expand Down
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