feat(blockifier): verify cairo-lang version before Cairo0 compilation

crates/blockifier/src/test_utils/cairo_compile.rs

@@ -1,8 +1,11 @@
 use std::process::Command;
+use std::{env, fs};
 
 use cached::proc_macro::cached;
 use serde::{Deserialize, Serialize};
 
+const CAIRO0_PIP_REQUIREMENTS_FILE: &str = "tests/requirements.txt";
+
 /// Objects for simple deserialization of Cargo.toml to fetch the Cairo1 compiler version.
 /// The compiler itself isn't actually a dependency, so we compile by using the version of the
 /// cairo-lang-casm crate.
@@ -54,6 +57,7 @@ pub fn cairo1_compiler_version() -> String {
 
 /// Compiles a Cairo0 program using the deprecated compiler.
 pub fn cairo0_compile(path: String, extra_arg: Option<String>, debug_info: bool) -> Vec<u8> {
+    verify_cairo0_compiler_deps();
     let mut command = Command::new("starknet-compile-deprecated");
     command.arg(&path);
     if let Some(extra_arg) = extra_arg {
@@ -72,3 +76,34 @@ pub fn cairo0_compile(path: String, extra_arg: Option<String>, debug_info: bool)
 pub fn cairo1_compile(_path: String) -> Vec<u8> {
     todo!();
 }
+
+/// Verifies that the required dependencies are available before compiling; panics if unavailable.
+fn verify_cairo0_compiler_deps() {
+    // Python compiler. Verify correct version.
+    let cairo_lang_version_output =
+        Command::new("sh").arg("-c").arg("pip freeze | grep cairo-lang").output().unwrap().stdout;
+    let cairo_lang_version_untrimmed = String::from_utf8(cairo_lang_version_output).unwrap();
+    let cairo_lang_version = cairo_lang_version_untrimmed.trim();
+    let requirements_contents = fs::read_to_string(CAIRO0_PIP_REQUIREMENTS_FILE).unwrap();
+    let expected_cairo_lang_version = requirements_contents
+        .lines()
+        .nth(1) // Skip docstring.
+        .expect(
+            "Expecting requirements file to contain a docstring in the first line, and \
+            then the required cairo-lang version in the second line."
+        ).trim();
+
+    assert_eq!(
+        cairo_lang_version,
+        expected_cairo_lang_version,
+        "cairo-lang version {expected_cairo_lang_version} not found ({}). Please run:\npip3.9 \
+         install -r {}/{}\nthen rerun the test.",
+        if cairo_lang_version.is_empty() {
+            String::from("no installed cairo-lang found")
+        } else {
+            format!("installed version: {cairo_lang_version}")
+        },
+        env::var("CARGO_MANIFEST_DIR").unwrap(),
+        CAIRO0_PIP_REQUIREMENTS_FILE
+    );
+}