feat(random): add random-chars (#390)

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

@@ -0,0 +1,89 @@
+use nu_engine::CallExt;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Value};
+use rand::{
+    distributions::{Alphanumeric, Distribution},
+    thread_rng,
+};
+
+const DEFAULT_CHARS_LENGTH: usize = 25;
+
+#[derive(Clone)]
+pub struct SubCommand;
+
+impl Command for SubCommand {
+    fn name(&self) -> &str {
+        "random chars"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("random chars")
+            .named("length", SyntaxShape::Int, "Number of chars", Some('l'))
+            .category(Category::Random)
+    }
+
+    fn usage(&self) -> &str {
+        "Generate random chars"
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        chars(engine_state, stack, call)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Generate random chars",
+                example: "random chars",
+                result: None,
+            },
+            Example {
+                description: "Generate random chars with specified length",
+                example: "random chars -l 20",
+                result: None,
+            },
+        ]
+    }
+}
+
+fn chars(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    call: &Call,
+) -> Result<PipelineData, ShellError> {
+    let span = call.head;
+    let length: Option<usize> = call.get_flag(engine_state, stack, "length")?;
+
+    let chars_length = length.unwrap_or(DEFAULT_CHARS_LENGTH);
+    let mut rng = thread_rng();
+
+    let random_string = Alphanumeric
+        .sample_iter(&mut rng)
+        .take(chars_length)
+        .map(char::from)
+        .collect::<String>();
+
+    Ok(PipelineData::Value(Value::String {
+        val: random_string,
+        span,
+    }))
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

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

@@ -1,5 +1,7 @@
 mod bool;
+mod chars;
 mod command;
 
 pub use self::bool::SubCommand as Bool;
+pub use self::chars::SubCommand as Chars;
 pub use command::RandomCommand as Random;