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davearonson's solution

to Two Fer in the Elixir Track

Published at Jul 20 2019 · 0 comments
Instructions
Test suite
Solution

Note:

This exercise has changed since this solution was written.

Two-fer or 2-fer is short for two for one. One for you and one for me.

"One for X, one for me."

When X is a name or "you".

If the given name is "Alice", the result should be "One for Alice, one for me." If no name is given, the result should be "One for you, one for me."

Running tests

Execute the tests with:

$ elixir two_fer_test.exs

Pending tests

In the test suites, all but the first test have been skipped.

Once you get a test passing, you can unskip the next one by commenting out the relevant @tag :pending with a # symbol.

For example:

# @tag :pending
test "shouting" do
  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
end

Or, you can enable all the tests by commenting out the ExUnit.configure line in the test suite.

# ExUnit.configure exclude: :pending, trace: true

If you're stuck on something, it may help to look at some of the available resources out there where answers might be found.

Source

https://en.wikipedia.org/wiki/Two-fer

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

two_fer_test.exs

if !System.get_env("EXERCISM_TEST_EXAMPLES") do
  Code.load_file("two_fer.exs", __DIR__)
end

ExUnit.start()
ExUnit.configure(exclude: :pending, trace: true)

defmodule TwoFerTest do
  use ExUnit.Case

  test "no name given" do
    assert TwoFer.two_fer() == "One for you, one for me"
  end

  @tag :pending
  test "a name given" do
    assert TwoFer.two_fer("Gilberto Barros") == "One for Gilberto Barros, one for me"
  end

  @tag :pending
  test "when the parameter is a number" do
    assert_raise FunctionClauseError, fn ->
      TwoFer.two_fer(10)
    end
  end

  @tag :pending
  test "when the parameter is an atom" do
    assert_raise FunctionClauseError, fn ->
      TwoFer.two_fer(:bob)
    end
  end

  @tag :pending
  test "when the parameter is a charlist" do
    assert_raise FunctionClauseError, fn ->
      refute TwoFer.two_fer('Jon Snow')
    end
  end
end
defmodule TwoFer do
  @doc """
  Two-fer or 2-fer is short for two for one. One for you and one for me.
  """
  @default_name "you"
  @spec two_fer(String.t()) :: String.t()
  def two_fer(),    do: two_fer(@default_name)
  def two_fer(""),  do: two_fer(@default_name)
  def two_fer(name) when is_binary(name), do: "One for #{name}, one for me"
end

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