add argument --counts to run repeated tests, benchmarks

src/bin/cargo/commands/bench.rs

@@ -46,6 +46,7 @@ pub fn cli() -> App {
             "no-fail-fast",
             "Run all benchmarks regardless of failure",
         ))
+        .arg_counts()
         .arg_unit_graph()
         .after_help("Run `cargo help bench` for more detailed information.\n")
 }
@@ -65,6 +66,7 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     let ops = TestOptions {
         no_run: args.is_present("no-run"),
         no_fail_fast: args.is_present("no-fail-fast"),
+        counts: args.value_of_u32("counts")?,
         compile_opts,
     };
 

src/bin/cargo/commands/test.rs

@@ -40,6 +40,7 @@ pub fn cli() -> App {
         .arg(opt("doc", "Test only this library's documentation"))
         .arg(opt("no-run", "Compile, but don't run tests"))
         .arg(opt("no-fail-fast", "Run all tests regardless of failure"))
+        .arg_counts()
         .arg_package_spec(
             "Package to run tests for",
             "Test all packages in the workspace",
@@ -117,6 +118,7 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     let ops = ops::TestOptions {
         no_run,
         no_fail_fast: args.is_present("no-fail-fast"),
+        counts: args.value_of_u32("counts")?,
         compile_opts,
     };
 

src/cargo/ops/cargo_test.rs

@@ -11,6 +11,7 @@ pub struct TestOptions {
     pub compile_opts: ops::CompileOptions,
     pub no_run: bool,
     pub no_fail_fast: bool,
+    pub counts: Option<u32>,
 }
 
 pub fn run_tests(
@@ -113,18 +114,20 @@ fn run_unit_tests(
             .shell()
             .verbose(|shell| shell.status("Running", &cmd))?;
 
-        let result = cmd.exec();
+        for _ in 0..options.counts.unwrap_or(1) {
+            let result = cmd.exec();
 
-        if let Err(e) = result {
-            let e = e.downcast::<ProcessError>()?;
-            errors.push((
-                unit.target.kind().clone(),
-                unit.target.name().to_string(),
-                unit.pkg.name().to_string(),
-                e,
-            ));
-            if !options.no_fail_fast {
-                break;
+            if let Err(e) = result {
+                let e = e.downcast::<ProcessError>()?;
+                errors.push((
+                    unit.target.kind().clone(),
+                    unit.target.name().to_string(),
+                    unit.pkg.name().to_string(),
+                    e,
+                ));
+                if !options.no_fail_fast {
+                    break;
+                }
             }
         }
     }

src/cargo/util/command_prelude.rs

@@ -66,6 +66,14 @@ pub trait AppExt: Sized {
         )
     }
 
+    fn arg_counts(self) -> Self {
+        self._arg(
+            opt("counts", "Number of repeated runs, default to 1")
+                .short("c")
+                .value_name("N"),
+        )
+    }
+
     fn arg_jobs(self) -> Self {
         self._arg(
             opt("jobs", "Number of parallel jobs, defaults to # of CPUs")

tests/testsuite/bench.rs

@@ -1756,3 +1756,34 @@ fn json_artifact_includes_executable_for_benchmark() {
         )
         .run();
 }
+
+#[cargo_test]
+fn cargo_bench_counts() {
+    if !is_nightly() {
+        return;
+    }
+
+    let p = project()
+        .file("Cargo.toml", &basic_bin_manifest("foo"))
+        .file(
+            "src/main.rs",
+            r#"
+                #![feature(test)]
+                #[cfg(test)]
+                extern crate test;
+                fn main() {}
+                #[bench] fn bench_hello(_b: &mut test::Bencher) {}
+            "#,
+        )
+        .build();
+
+    p.cargo("bench --counts 4")
+        .with_stderr(
+            "\
+[COMPILING] foo v0.5.0 ([CWD])
+[FINISHED] bench [optimized] target(s) in [..]
+[RUNNING] [..] (target/release/deps/foo-[..][EXE])",
+        )
+        .with_stdout_contains_n("test bench_hello ... bench: [..]", 4)
+        .run();
+}

tests/testsuite/test.rs

@@ -4455,3 +4455,28 @@ fn test_workspaces_cwd() {
         .with_stdout_contains("test test_integration_deep_cwd ... ok")
         .run();
 }
+
+#[cargo_test]
+fn cargo_test_counts() {
+    let p = project()
+        .file("Cargo.toml", &basic_bin_manifest("foo"))
+        .file(
+            "src/main.rs",
+            r#"
+                fn main() {}
+                #[test] fn test_hello() {}
+            "#,
+        )
+        .build();
+
+    p.cargo("test -c 4")
+        .with_stderr(
+            "\
+[COMPILING] foo v0.5.0 ([CWD])
+[FINISHED] test [unoptimized + debuginfo] target(s) in [..]
+[RUNNING] [..] (target/debug/deps/foo-[..][EXE])
+",
+        )
+        .with_stdout_contains_n("test test_hello ... ok", 4)
+        .run();
+}