todo.md

Homework

2022/10/14

Basic

• Test Rational normalize properly when you apply the class. Spoiler by David: You want to test that multiplying both numerator and denominator by the same integer (non-zero) value, you get the same normalized value you started with.
• Create a class Natural for natural numbers so that you can't possibly create an instance of Natural with a non positive value. Implement addition and multiplication.
• Write property based tests for Naturals addition.

Intermediate

• Enhance Rational.+ to support bigger Int values. Hint: Use mcmc. (by Adrià)
• Design a class Json that can represent strings, booleans, numbers, nulls, objects and arrays
• Implement a function Json.asString() that returns the string implementation of your Json and a function Json.parse(s: String): Try[Json] that tries to parse a string into an instance of Json.
• Write property based tests of parse and asString. You will need to define an Arbitrary[Json] and that will require combinators we still don't have. Try to generalize them properly to be used in other contexts. Hint: Generate random strings that do not contain quotes and random integers for numbers (don't try to make floating point arithmetic work here).

2022/10/07

(Not so) Basic

• Implement a Rational class in com.agillogy.wpbtl.examples.main under src/test as a case class of the numerator and the denominator.
• Implement the operator + on Rational.
• Write property based tests of the sum of rationals. You'll need a way of creating an Arbitrary[Rational]. Use pair and map to build one.

Intermediate

• Rewrite your Arbitrary[Rational] to avoid the unnecessary creation of a Tuple2.

  • Clue: Create a new combinator not tied to Rational. See the TODO comments in the source code

• Create combinators like the one you created for Rational for arities 3 and 4.

• Rewrite the pair combinator to avoid code repetition with the ones you just wrote.

Advanced

Remember: Advanced tasks won't be generally solved in this repository

• Somehow generalize the combinators you created to combine 2, 3 or 4 instances of Arbitrary to any number of instances. If you can't reason about the limits of such generalization.

2022/09/30

Basic

• Separate example tests (which test sum) from the own library tests (which test forAll)
• Read these blog entries about testing:
  • What is an automated test, again?
  • Testing and persistent state
  • Testing other side effects

Intermediate

• Write property based tests of string concatenation. Think about what properties to test and write tests as usage examples of the library.

Advanced

Remember: Advanced tasks won't be generally solved in this repository

• Write property based tests about forAll: "For all properties of integers, if I check that property, then the outcome has these properties."

  • Clue:

  forAll(intPropertyArb){
    val result = Try(forAll(arbInt){intPropertyArb})
    // Assertions about the result
  }