Add random mutation tests

cli/src/tests/random.rs

@@ -0,0 +1,41 @@
+use rand::distributions::Alphanumeric;
+use rand::prelude::{Rng, SeedableRng, SmallRng};
+
+const OPERATORS: &[char] = &[
+    '+', '-', '<', '>', '(', ')', '*', '/', '&', '|', '!', ',', '.',
+];
+
+pub struct Rand(SmallRng);
+
+impl Rand {
+    pub fn new(seed: usize) -> Self {
+        Rand(SmallRng::seed_from_u64(seed as u64))
+    }
+
+    pub fn unsigned(&mut self, max: usize) -> usize {
+        self.0.gen_range(0, max + 1)
+    }
+
+    pub fn words(&mut self, max_count: usize) -> Vec<u8> {
+        let mut result = Vec::new();
+        let word_count = self.unsigned(max_count);
+        for i in 0..word_count {
+            if i > 0 {
+                if self.unsigned(5) == 0 {
+                    result.push('\n' as u8);
+                } else {
+                    result.push(' ' as u8);
+                }
+            }
+            if self.unsigned(3) == 0 {
+                let index = self.unsigned(OPERATORS.len() - 1);
+                result.push(OPERATORS[index] as u8);
+            } else {
+                for _ in 0..self.unsigned(8) {
+                    result.push(self.0.sample(Alphanumeric) as u8);
+                }
+            }
+        }
+        result
+    }
+}