Don't hardcode "cargo" tool name

Author: sourcefrog

src/cargo.rs

@@ -37,6 +37,10 @@ impl CargoTool {
 }
 
 impl Tool for CargoTool {
+    fn name(&self) -> &str {
+        "cargo"
+    }
+
     fn find_root(&self, path: &Utf8Path) -> Result<Utf8PathBuf> {
         let cargo_toml_path = locate_cargo_toml(path)?;
         let root = cargo_toml_path

src/lab.rs

@@ -63,7 +63,8 @@ pub fn test_unmutated_then_all_mutants(
     };
     if !baseline_outcome.success() {
         error!(
-            "cargo {} failed in an unmutated tree, so no mutants were tested",
+            "{} {} failed in an unmutated tree, so no mutants were tested",
+            tool.name(),
             baseline_outcome.last_phase(),
         );
         // TODO: Maybe should be Err, but it would need to be an error that can map to the right

src/tool.rs

@@ -21,6 +21,8 @@ use crate::Result;
 use crate::SourceFile;
 
 pub trait Tool: Debug + Send + Sync {
+    fn name(&self) -> &str;
+
     /// Find the root of the package enclosing a given path.
     ///
     /// The root is the enclosing directory that needs to be copied to make a self-contained