Disallow std::env::var (#177)

build.rs

@@ -31,6 +31,7 @@ use fs_err as fs;
 fn main() {
     // The workspace root directory is not available without walking up the tree
     // https://github.com/rust-lang/cargo/issues/3946
+    #[allow(clippy::disallowed_methods)]
     let workspace_root = Path::new(&std::env::var("CARGO_MANIFEST_DIR").unwrap()).to_path_buf();
 
     commit_info(&workspace_root);

clippy.toml

@@ -0,0 +1,4 @@
+disallowed-methods = [
+    "std::env::var",
+    "std::env::var_os",
+]

lib/constants/src/env_vars.rs

@@ -35,6 +35,7 @@ impl EnvVars {
 impl EnvVars {
     /// Read an environment variable, falling back to pre-commit corresponding variable if not found.
     pub fn var_os(name: &str) -> Option<OsString> {
+        #[allow(clippy::disallowed_methods)]
         std::env::var_os(name).or_else(|| {
             if let Some(name) = Self::pre_commit_name(name) {
                 if let Some(val) = std::env::var_os(name) {

tests/common/mod.rs

@@ -1,6 +1,5 @@
 #![allow(dead_code, unreachable_pub)]
 
-use std::env;
 use std::ffi::OsStr;
 use std::path::{Path, PathBuf};
 use std::process::Command;
@@ -65,7 +64,7 @@ impl TestContext {
     }
 
     pub fn test_bucket_dir() -> PathBuf {
-        env::var(EnvVars::PREFLIGIT_INTERNAL__TEST_DIR)
+        EnvVars::var(EnvVars::PREFLIGIT_INTERNAL__TEST_DIR)
             .map(PathBuf::from)
             .unwrap_or_else(|_| {
                 etcetera::base_strategy::choose_base_strategy()