Allow user to set output dir for regression tests via env var

Author: alexdewar

tests/regression.rs

@@ -4,10 +4,11 @@ use itertools::Itertools;
 use muse2::cli::RunOpts;
 use muse2::cli::example::handle_example_run_command;
 use muse2::settings::Settings;
+use std::env;
 use std::fs::{File, read_dir};
 use std::io::{BufRead, BufReader};
 use std::path::{Path, PathBuf};
-use tempfile::tempdir;
+use tempfile::{TempDir, tempdir};
 
 const FLOAT_CMP_TOLERANCE: f64 = 1e-10;
 
@@ -27,19 +28,27 @@ pub fn run_regression_test_with_debug_files(example_name: &str) {
 }
 
 fn run_regression_test_debug_opt(example_name: &str, debug_model: bool) {
-    unsafe { std::env::set_var("MUSE2_LOG_LEVEL", "off") };
+    unsafe { env::set_var("MUSE2_LOG_LEVEL", "off") };
+
+    // Allow user to set output dir for regression tests so they can examine results. This is
+    // principally intended for use by CI.
+    let tmp: TempDir;
+    let output_dir = if let Ok(dir) = env::var("MUSE2_TEST_OUTPUT_DIR") {
+        [&dir, example_name].iter().collect()
+    } else {
+        tmp = tempdir().unwrap();
+        tmp.path().to_path_buf()
+    };
 
-    let tempdir = tempdir().unwrap();
     let opts = RunOpts {
-        output_dir: Some(tempdir.path().to_path_buf()),
+        output_dir: Some(output_dir.clone()),
         overwrite: false,
         debug_model,
     };
-    let output_dir = tempdir.path();
     handle_example_run_command(example_name, &opts, Some(Settings::default())).unwrap();
 
     let test_data_dir = PathBuf::from(format!("tests/data/{example_name}"));
-    compare_output_dirs(output_dir, &test_data_dir);
+    compare_output_dirs(&output_dir, &test_data_dir);
 }
 
 fn compare_output_dirs(output_dir1: &Path, output_dir2: &Path) {