Parallelize prompt modules (#46)

benches/my_benchmark.rs

@@ -6,6 +6,8 @@ use criterion::Criterion;
 use clap::{App, Arg};
 use starship::context::Context;
 use starship::modules;
+use std::fs;
+use tempfile::TempDir;
 
 fn char_segment(c: &mut Criterion) {
     let args = App::new("starship")
@@ -40,5 +42,28 @@ fn line_break_segment(c: &mut Criterion) {
     });
 }
 
-criterion_group!(benches, dir_segment, char_segment, line_break_segment);
+fn git_branch_segment(c: &mut Criterion) {
+    let tmp_dir = TempDir::new().unwrap();
+    let repo_dir = tmp_dir.path().join("rocket-controls");
+    fs::create_dir(&repo_dir).unwrap();
+
+    git2::Repository::init(&repo_dir).unwrap();
+
+    let args = App::new("starship")
+        .arg(Arg::with_name("status_code"))
+        .get_matches_from(vec!["starship", "0"]);
+    let context = Context::new_with_dir(args, "~");
+
+    c.bench_function("git_branch segment", move |b| {
+        b.iter(|| modules::handle("git_branch", &context))
+    });
+}
+
+criterion_group!(
+    benches,
+    char_segment,
+    dir_segment,
+    line_break_segment,
+    git_branch_segment
+);
 criterion_main!(benches);