Create random binary command (#13542)

# Description/User-Facing Changes

Creates a new `random binary <LENGTH>` command, which returns random
bytes.

Resolve #13500

crates/nu-command/src/default_context.rs

@@ -397,6 +397,7 @@ pub fn add_shell_command_context(mut engine_state: EngineState) -> EngineState {
             RandomFloat,
             RandomInt,
             RandomUuid,
+            RandomBinary
         };
 
         // Generators

crates/nu-command/src/random/binary.rs

@@ -0,0 +1,64 @@
+use nu_engine::command_prelude::*;
+
+use rand::{thread_rng, RngCore};
+
+#[derive(Clone)]
+pub struct SubCommand;
+
+impl Command for SubCommand {
+    fn name(&self) -> &str {
+        "random binary"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("random binary")
+            .input_output_types(vec![(Type::Nothing, Type::Binary)])
+            .allow_variants_without_examples(true)
+            .required("length", SyntaxShape::Int, "Length of the output binary.")
+            .category(Category::Random)
+    }
+
+    fn usage(&self) -> &str {
+        "Generate random bytes."
+    }
+
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["generate", "bytes"]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let length = call.req(engine_state, stack, 0)?;
+        let mut rng = thread_rng();
+
+        let mut out = vec![0u8; length];
+        rng.fill_bytes(&mut out);
+
+        Ok(Value::binary(out, call.head).into_pipeline_data())
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Generate 16 random bytes",
+            example: "random bytes 16",
+            result: None,
+        }]
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

crates/nu-command/src/random/mod.rs

@@ -1,3 +1,4 @@
+mod binary;
 mod bool;
 mod chars;
 mod dice;
@@ -6,6 +7,7 @@ mod int;
 mod random_;
 mod uuid;
 
+pub use self::binary::SubCommand as RandomBinary;
 pub use self::bool::SubCommand as RandomBool;
 pub use self::chars::SubCommand as RandomChars;
 pub use self::dice::SubCommand as RandomDice;