add cargo backend

src/backend/rust.rs

@@ -0,0 +1,76 @@
+use std::{collections::HashSet, process::Command};
+
+use super::{Backend, Binary, Switches};
+use crate::Package;
+
+pub struct Rust;
+
+impl Backend for Rust {
+    const BINARY: Binary = "cargo";
+    const SWITCHES_INSTALL: Switches = &["install"];
+    const SWITCHES_REMOVE: Switches = &["uninstall"];
+
+    fn get_all_installed_packages() -> HashSet<Package> {
+        extract_packages_names(&run_cargo_install_list())
+            .map(Package::from)
+            .collect()
+    }
+
+    fn get_explicitly_installed_packages() -> HashSet<Package> {
+        Self::get_all_installed_packages()
+    }
+}
+
+fn run_cargo_install_list() -> String {
+    let stdout = Command::new("cargo")
+        .args(["install", "--list"])
+        .output()
+        .unwrap()
+        .stdout;
+    String::from_utf8(stdout).unwrap()
+}
+
+fn extract_packages_names(output: &str) -> impl Iterator<Item = String> + '_ {
+    output
+        .lines()
+        .filter(|line| !line.starts_with(char::is_whitespace))
+        .map(|line| line.split_whitespace().next().unwrap().to_owned())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::extract_packages_names;
+
+    #[test]
+    fn test_extract_packages() {
+        const OUTPUT: &str = "cargo-audit v0.17.4:
+    cargo-audit
+cargo-cache v0.8.3:
+    cargo-cache
+cargo-criterion v1.1.0:
+    cargo-criterion
+cargo-update v11.1.1:
+    cargo-install-update
+    cargo-install-update-config
+flamegraph v0.6.2:
+    cargo-flamegraph
+    flamegraph
+topgrade v10.1.2 (/home/ratajc72/tmp/topgrade):
+    topgrade
+wthrr v0.6.1:
+    wthrr";
+        let extracted: Vec<String> = extract_packages_names(OUTPUT).collect();
+        assert_eq!(
+            &extracted,
+            &[
+                "cargo-audit",
+                "cargo-cache",
+                "cargo-criterion",
+                "cargo-update",
+                "flamegraph",
+                "topgrade",
+                "wthrr"
+            ]
+        );
+    }
+}