Update tests with basic init

src/debug.rs

@@ -0,0 +1,53 @@
+use std::num::NonZeroUsize;
+
+pub struct DebugLog {
+    current: String,
+    history: Vec<String>,
+    max_history: Option<NonZeroUsize>,
+    pos: usize,
+}
+
+impl DebugLog {
+    pub fn new() -> Self {
+        Self {
+            current: String::new(),
+            history: vec![],
+            max_history: None,
+            pos: 0,
+        }
+    }
+
+    pub fn rotate(&mut self) {
+        let rot = std::mem::take(&mut self.current);
+        if let Some(max) = self.max_history {
+            if self.history.len() < max.into() {
+                self.history.push(rot);
+            } else {
+                self.history[self.pos] = rot;
+                self.pos = (self.pos + 1) % max.get();
+            }
+        } else {
+            self.history.push(rot);
+        }
+    }
+}
+
+impl std::fmt::Write for DebugLog {
+    fn write_str(&mut self, s: &str) -> std::fmt::Result {
+        self.current.write_str(s)
+    }
+
+    fn write_char(&mut self, c: char) -> std::fmt::Result {
+        self.current.write_char(c)
+    }
+
+    fn write_fmt(&mut self, args: std::fmt::Arguments<'_>) -> std::fmt::Result {
+        self.current.write_fmt(args)
+    }
+}
+
+impl Default for DebugLog {
+    fn default() -> Self {
+        Self::new()
+    }
+}