Testing And Benchmarking in Crystal

Here’s the translation of the Go testing and benchmarking example to Crystal:

# Unit testing is an important part of writing principled Crystal programs.
# Crystal comes with a built-in testing framework that provides the tools
# we need to write unit tests.

# For the sake of demonstration, this code is in the global namespace,
# but it could be in any module. Testing code typically lives in the
# same file as the code it tests, in a separate `spec` block.

# We'll be testing this simple implementation of an integer minimum.
def int_min(a : Int32, b : Int32) : Int32
  a < b ? a : b
end

# Tests are created by writing specs inside a `describe` block.
describe "IntMin" do
  # A basic test
  it "returns the minimum of two numbers" do
    int_min(2, -2).should eq(-2)
  end

  # Writing tests can be repetitive, so it's idiomatic to use
  # a data-driven style, where test inputs and expected outputs
  # are listed in an array and a single loop walks over them
  # and performs the test logic.
  [
    {a: 0, b: 1, expected: 0},
    {a: 1, b: 0, expected: 0},
    {a: 2, b: -2, expected: -2},
    {a: 0, b: -1, expected: -1},
    {a: -1, b: 0, expected: -1},
  ].each do |test_case|
    it "returns #{test_case[:expected]} for #{test_case[:a]} and #{test_case[:b]}" do
      int_min(test_case[:a], test_case[:b]).should eq(test_case[:expected])
    end
  end
end

# Benchmark tests in Crystal are typically created using the `Benchmark` module.
# Here's an example of how you might benchmark the `int_min` function:

require "benchmark"

Benchmark.ips do |x|
  x.report("int_min") { int_min(1, 2) }
end

To run the tests, you would typically save this code in a file with a .cr extension (e.g., int_min_spec.cr) and then use the crystal spec command:

$ crystal spec int_min_spec.cr

This will run all the tests and display the results.

To run the benchmark, you would typically put the benchmark code in a separate file (e.g., int_min_benchmark.cr) and run it with:

$ crystal run int_min_benchmark.cr

This will execute the benchmark and display the results, showing how many iterations per second the int_min function can perform.

Note that Crystal’s testing and benchmarking approach is quite different from Go’s. Crystal uses a behavior-driven development (BDD) style for testing, which is more similar to RSpec in Ruby. For benchmarking, Crystal provides the Benchmark module, which is different from Go’s testing.B approach but serves a similar purpose.

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Testing And Benchmarking in Crystal