test: Test all logger level case variants

Signed-off-by: Jonathan Woollett-LIght <jcawl@amazon.co.uk>

src/vmm/Cargo.toml

@@ -38,6 +38,7 @@ base64 = "0.13.0"
 bincode = "1.2.1"
 micro_http = { git = "https://github.com/firecracker-microvm/micro-http" }
 log-instrument = { path = "../log-instrument", optional = true }
+itertools = "0.12.0"
 
 seccompiler = { path = "../seccompiler" }
 snapshot = { path = "../snapshot"}

src/vmm/src/logger/logging.rs

@@ -304,6 +304,23 @@ mod tests {
         );
     }
     #[test]
+    fn levelfilter_from_str_all_variants() {
+        use itertools::Itertools;
+
+        for level in ["off","trace","debug","info","warn","error"] {
+            let mut multi = level.chars().map(|_|0..=1).multi_cartesian_product()();
+            for combination in multi {
+                let variant = level.chars().zip_eq(combination).map(|(c,v)| match v {
+                    0 => c.to_lowercase(),
+                    1 => c.to_uppercase(),
+                    _ => unreachable!()
+                }).collect::<String>();
+                assert!(LevelFilter::from_str(&variant).is_ok());
+                assert!(serde_json::from_str::<_, LevelFilter>(&variant).is_ok());
+            }
+        }
+    }
+    #[test]
     fn levelfilter_from_str() {
         assert_eq!(
             LevelFilter::from_str("bad"),