feat: add 'timeout-multiplier' flag to config file

book/src/timeouts.md

@@ -31,6 +31,6 @@ You can also set an explicit timeout with the `--timeout` option, also measured
 in seconds. If this option is specified then the timeout is also applied to the
 unmutated tests.
 
-You can set a timeout multiplier that is relative to the duration of the unmutated tests with `--timeout-multiplier`. This option is only applied if the baseline is not skipped and no `--timeout` option is specified, otherwise it is ignored.
+You can set a timeout multiplier that is relative to the duration of the unmutated tests with `--timeout-multiplier` or setting `timeout_multiplier` in `.cargo/mutants.toml` (`timeout-multiplier = 1.5`). This option is only applied if the baseline is not skipped and no `--timeout` option is specified, otherwise it is ignored.
 
 The timeout does not apply to `cargo check` or `cargo build`, only `cargo test`.

src/config.rs

@@ -44,6 +44,8 @@ pub struct Config {
     pub minimum_test_timeout: Option<f64>,
     /// Choice of test tool: cargo or nextest.
     pub test_tool: Option<TestTool>,
+    /// Timeout multiplier, relative to the baseline 'cargo test'.
+    pub timeout_multiplier: Option<f64>,
 }
 
 impl Config {

src/options.rs

@@ -210,7 +210,7 @@ impl Options {
             show_times: !args.no_times,
             show_all_logs: args.all_logs,
             test_timeout: args.timeout.map(Duration::from_secs_f64),
-            test_timeout_multiplier: args.timeout_multiplier,
+            test_timeout_multiplier: config.timeout_multiplier.or(args.timeout_multiplier),
             test_tool: args.test_tool.or(config.test_tool).unwrap_or_default(),
         };
         options.error_values.iter().for_each(|e| {