slightly better logging

crates/desktop/artcraft/src/core/lifecycle/startup/tasks/set_app_log_level.rs

@@ -13,25 +13,38 @@ pub fn set_app_log_level(
   root: &AppDataRoot,
 ) -> AnyhowResult<()> {
 
-  print_env_var(RUST_LOG);
+  //print_env_var(RUST_LOG);
 
   // NB: The semantics of this do not match `RUST_LOG` exactly as it's not set per-package.
-  let level = env::var(RUST_LOG)
-      .map(|value| value.trim().to_ascii_lowercase())
-      .unwrap_or("info".to_string());
+  let maybe_level = env::var(RUST_LOG)
+      .map(|value| value.trim().to_ascii_lowercase());
 
   let mut log_level = LevelFilter::Info;
 
-  if level.contains("debug") {
-    log_level = LevelFilter::Debug;
-  } else if level.contains("info") {
-    log_level = LevelFilter::Info;
-  } else if level.contains("warn") {
-    log_level = LevelFilter::Warn;
-  } else if level.contains("error") {
-    log_level = LevelFilter::Error;
-  } else if level.contains("off") {
-    log_level = LevelFilter::Off;
+  match maybe_level {
+    Ok(level) => {
+      println!("The `RUST_LOG` environment variable was set to: `{}`.", level);
+
+      if level.contains("debug") {
+        log_level = LevelFilter::Debug;
+      } else if level.contains("info") {
+        log_level = LevelFilter::Info;
+      } else if level.contains("warn") {
+        log_level = LevelFilter::Warn;
+      } else if level.contains("error") {
+        log_level = LevelFilter::Error;
+      } else if level.contains("off") {
+        log_level = LevelFilter::Off;
+      }
+    }
+    Err(VarError::NotPresent) => {
+      // NB: This demonstrably tests stderr output in the default case.
+      eprintln!("No `RUST_LOG` environment variable found.");
+    }
+    Err(VarError::NotUnicode(_)) => {
+      // NB: This demonstrably tests stderr output in the default case.
+      eprintln!("Could not parse `RUST_LOG` environment variable; not unicode.");
+    }
   }
 
   println!("Setting app log level to: {:?}", log_level);
@@ -51,10 +64,10 @@ pub fn set_app_log_level(
   Ok(())
 }
 
-pub fn print_env_var(var_name: &str) {
-  match env::var(var_name) {
-    Ok(value) => println!("Environment variable `{}` = {}", var_name, value),
-    Err(VarError::NotPresent) => println!("Environment variable `{}` is not set.", var_name),
-    Err(VarError::NotUnicode(_)) => println!("Environment variable `{}` is not a valid Unicode string", var_name),
-  }
-}
+// pub fn print_env_var(var_name: &str) {
+//   match env::var(var_name) {
+//     Ok(value) => println!("Environment variable `{}` = {}", var_name, value),
+//     Err(VarError::NotPresent) => println!("Environment variable `{}` is not set.", var_name),
+//     Err(VarError::NotUnicode(_)) => println!("Environment variable `{}` is not a valid Unicode string", var_name),
+//   }
+// }