chore(nargo): add integration test for "hello world" flow

crates/nargo/Cargo.toml

@@ -38,6 +38,11 @@ aztec_backend = { optional = true, package = "barretenberg_static_lib", git = "h
 aztec_wasm_backend = { optional = true, package = "barretenberg_wasm", git = "https://github.com/noir-lang/aztec_backend", rev = "2cb523d2ab95249157b22e198d9dcd6841c3eed8" }
 marlin_arkworks_backend = { optional = true, git = "https://github.com/noir-lang/marlin_arkworks_backend", rev = "144378edad821bfaa52bf2cacca8ecc87514a4fc" }
 
+[dev-dependencies]
+assert_cmd = "2.0.8"
+assert_fs = "1.0.10"
+predicates = "2.1.5"
+
 [features]
 default = ["plonk_bn254"]
 # The plonk backend can only use bn254, so we do not specify the field

crates/nargo/tests/hello_world.rs

@@ -0,0 +1,56 @@
+//! This integration test aims to mirror the steps taken by a new user using Nargo for the first time.
+//! It then follows the steps published at https://noir-lang.org/getting_started/hello_world.html
+//! Any modifications to the commands run here MUST be documented in the noir-lang book.
+
+use assert_cmd::prelude::*;
+use predicates::prelude::*;
+use std::process::Command;
+
+use assert_fs::prelude::{FileWriteStr, PathAssert, PathChild};
+
+#[test]
+fn hello_world_example() {
+    let test_dir = assert_fs::TempDir::new().unwrap();
+    std::env::set_current_dir(&test_dir).unwrap();
+
+    let project_name = "hello_world";
+    let project_dir = test_dir.child(project_name);
+
+    // `nargo new hello_world`
+    let mut cmd = Command::cargo_bin("nargo").unwrap();
+    cmd.arg("new").arg(project_name);
+    cmd.assert().success().stdout(predicate::str::contains("Project successfully created!"));
+
+    project_dir.child("src").assert(predicate::path::is_dir());
+    project_dir.child("Nargo.toml").assert(predicate::path::is_file());
+
+    std::env::set_current_dir(&project_dir).unwrap();
+
+    // `nargo check`
+    let mut cmd = Command::cargo_bin("nargo").unwrap();
+    cmd.arg("check");
+    cmd.assert()
+        .success()
+        .stdout(predicate::str::contains("Constraint system successfully built!"));
+
+    project_dir.child("Prover.toml").assert(predicate::path::is_file());
+    project_dir.child("Verifier.toml").assert(predicate::path::is_file());
+
+    // `nargo prove p`
+    let proof_name = "p";
+    project_dir.child("Prover.toml").write_str("x = 1\ny = 2").unwrap();
+
+    let mut cmd = Command::cargo_bin("nargo").unwrap();
+    cmd.arg("prove").arg(proof_name);
+    cmd.assert().success();
+
+    project_dir
+        .child("proofs")
+        .child(format!("{proof_name}.proof"))
+        .assert(predicate::path::is_file());
+
+    // `nargo verify p`
+    let mut cmd = Command::cargo_bin("nargo").unwrap();
+    cmd.arg("verify").arg(proof_name);
+    cmd.assert().success();
+}