substrate-knowledge-map

Quiz 3: Basic Rust

Overview

This quiz covers the following parts of the Substrate Knowledge Map:

• Rust

1. What are some of Rust’s key strengths?

• A. Rust avoids 70% of all safety issues present in C / C++, and most memory issues.
• B. Rust comes with a modern tooling infrastructure: cargo (builds just work), clippy (300+ code quality lints) and rustup (toolchain mgmt).
• C. Rust is interoperable with other LLVM based platforms.
• D. All of the above.
• E. Only A and B.

2. In Substrate, Rust macros are useful because …

• A. Macros are a way to avoid code repetition.
• B. Macros enable developers to write domain specific languages.
• C. Macros allow metaprogramming.
• D. All of the above.

3. Which of these is correct syntax for a struct in Rust? Check all that apply.

• A.

  struct Pair(i32, f32);
  

• B.

  #[derive(Encode, Decode, Default, Clone, PartialEq)]
  pub struct MyStruct {
      some_number: u32,
      optional_number: Option<u32>,
  }
  

• C.

  #[pallet::weight(10_000 + T::DbWeight::get().writes(1))]
  pub fn do_something(origin: OriginFor<T>, something: u32) -> DispatchResult {
      let who = ensure_signed(origin)?;
      <Something<T>>::put(something);
      Ok(())
  }
  

• D.

  struct Person {
      char name[30];
      int citizenship;
      int age;
  }
  

4. What is true about unit testing in Rust? Check all that apply.

• A. assert!(expression) and assert_eq!(left, right) are useful helper macros to evaluate expressions.
• B. Tests can be run using cargo run test.
• C. Unit tests are more complex in Rust than in any other language.
• D. Most unit tests go into a tests mod with the #[cfg(test)] attribute.