space_age

elixir/space-age/.exercism/config.json

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+{
+  "authors": [
+    "rubysolo"
+  ],
+  "contributors": [
+    "angelikatyborska",
+    "Cohen-Carlisle",
+    "dalexj",
+    "devonestes",
+    "henrik",
+    "jinyeow",
+    "koriroys",
+    "kytrinyx",
+    "lpil",
+    "neenjaw",
+    "parkerl",
+    "pminten",
+    "sotojuan",
+    "Teapane",
+    "waiting-for-dev"
+  ],
+  "files": {
+    "solution": [
+      "lib/space_age.ex"
+    ],
+    "test": [
+      "test/space_age_test.exs"
+    ],
+    "example": [
+      ".meta/example.ex"
+    ]
+  },
+  "blurb": "Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.",
+  "source": "Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial.",
+  "source_url": "https://pine.fm/LearnToProgram/?Chapter=01"
+}

elixir/space-age/.exercism/metadata.json

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+{"track":"elixir","exercise":"space-age","id":"a5e01ddaed4e4e6187c5fa10c72075ab","url":"https://exercism.org/tracks/elixir/exercises/space-age","handle":"negrienko","is_requester":true,"auto_approve":false}

elixir/space-age/.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

elixir/space-age/.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+space_age-*.tar
+

elixir/space-age/HELP.md

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+# Help
+
+## Running the tests
+
+From the terminal, change to the base directory of the exercise then execute the tests with:
+
+```bash
+$ mix test
+```
+
+This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
+
+Documentation:
+
+* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
+* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
+
+## Pending tests
+
+In test suites of practice exercises, all but the first test have been tagged to be 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:
+
+```elixir
+# @tag :pending
+test "shouting" do
+  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
+end
+```
+
+If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
+
+```bash
+$ mix test --include pending
+```
+
+Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
+
+```elixir
+# ExUnit.configure(exclude: :pending, trace: true)
+```
+
+## Useful `mix test` options
+
+* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
+* `--failed` - runs only tests that failed the last time they ran
+* `--max-failures` - the suite stops evaluating tests when this number of test failures
+is reached
+* `--seed 0` - disables randomization so the tests in a single file will always be ran
+in the same order they were defined in
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit lib/space_age.ex` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
+- The [Elixir track's programming category on the forum](https://forum.exercism.org/c/programming/elixir)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.

elixir/space-age/README.md

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+# Space Age
+
+Welcome to Space Age on Exercism's Elixir Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Given an age in seconds, calculate how old someone would be on:
+
+- Mercury: orbital period 0.2408467 Earth years
+- Venus: orbital period 0.61519726 Earth years
+- Earth: orbital period 1.0 Earth years, 365.25 Earth days, or 31557600 seconds
+- Mars: orbital period 1.8808158 Earth years
+- Jupiter: orbital period 11.862615 Earth years
+- Saturn: orbital period 29.447498 Earth years
+- Uranus: orbital period 84.016846 Earth years
+- Neptune: orbital period 164.79132 Earth years
+
+So if you were told someone were 1,000,000,000 seconds old, you should
+be able to say that they're 31.69 Earth-years old.
+
+If you're wondering why Pluto didn't make the cut, go watch [this YouTube video][pluto-video].
+
+Note: The actual length of one complete orbit of the Earth around the sun is closer to 365.256 days (1 sidereal year).
+The Gregorian calendar has, on average, 365.2425 days.
+While not entirely accurate, 365.25 is the value used in this exercise.
+See [Year on Wikipedia][year] for more ways to measure a year.
+
+[pluto-video]: https://www.youtube.com/watch?v=Z_2gbGXzFbs
+[year]: https://en.wikipedia.org/wiki/Year#Summary
+
+## Source
+
+### Created by
+
+- @rubysolo
+
+### Contributed to by
+
+- @angelikatyborska
+- @Cohen-Carlisle
+- @dalexj
+- @devonestes
+- @henrik
+- @jinyeow
+- @koriroys
+- @kytrinyx
+- @lpil
+- @neenjaw
+- @parkerl
+- @pminten
+- @sotojuan
+- @Teapane
+- @waiting-for-dev
+
+### Based on
+
+Partially inspired by Chapter 1 in Chris Pine's online Learn to Program tutorial. - https://pine.fm/LearnToProgram/?Chapter=01

elixir/space-age/lib/space_age.ex

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+defmodule SpaceAge do
+  @type planet ::
+          :mercury
+          | :venus
+          | :earth
+          | :mars
+          | :jupiter
+          | :saturn
+          | :uranus
+          | :neptune
+
+  @planets ~w(mercury venus earth mars jupiter saturn uranus neptune)a
+
+  defguardp is_planet(planet) when planet in @planets
+
+  defp factor(:mercury), do: 0.2408467
+  defp factor(:venus), do: 0.61519726
+  defp factor(:earth), do: 1.0
+  defp factor(:mars), do: 1.8808158
+  defp factor(:jupiter), do: 11.862615
+  defp factor(:saturn), do: 29.447498
+  defp factor(:uranus), do: 84.016846
+  defp factor(:neptune), do: 164.79132
+
+  @doc """
+  Return the number of years a person that has lived for 'seconds' seconds is
+  aged on 'planet', or an error if 'planet' is not a planet.
+  """
+  @spec age_on(planet, pos_integer) :: {:ok, float} | {:error, String.t()}
+  def age_on(planet, seconds) when is_planet(planet),
+    do: {:ok, seconds / (factor(planet) * 31_557_600)}
+
+  def age_on(_planet, _seconds),
+    do: {:error, "not a planet"}
+end

elixir/space-age/mix.exs

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+defmodule SpaceAge.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :space_age,
+      version: "0.1.0",
+      # elixir: "~> 1.8",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
+    ]
+  end
+end

elixir/space-age/test/space_age_test.exs

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+defmodule SpaceAgeTest do
+  use ExUnit.Case
+
+  test "age on Earth" do
+    input = 1_000_000_000
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 31.69, age, 0.005
+  end
+
+  test "age on Mercury" do
+    input = 2_134_835_688
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 67.65, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:mercury, input)
+    assert_in_delta 280.88, age, 0.005
+  end
+
+  test "age on Venus" do
+    input = 189_839_836
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 6.02, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:venus, input)
+    assert_in_delta 9.78, age, 0.005
+  end
+
+  test "age on Mars" do
+    input = 2_129_871_239
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 67.49, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:mars, input)
+    assert_in_delta 35.88, age, 0.005
+  end
+
+  test "age on Jupiter" do
+    input = 901_876_382
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 28.58, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:jupiter, input)
+    assert_in_delta 2.41, age, 0.005
+  end
+
+  test "age on Saturn" do
+    input = 2_000_000_000
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 63.38, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:saturn, input)
+    assert_in_delta 2.15, age, 0.005
+  end
+
+  test "age on Uranus" do
+    input = 1_210_123_456
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 38.35, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:uranus, input)
+    assert_in_delta 0.46, age, 0.005
+  end
+
+  test "age on Neptune" do
+    input = 1_821_023_456
+    {:ok, age} = SpaceAge.age_on(:earth, input)
+    assert_in_delta 57.70, age, 0.005
+    {:ok, age} = SpaceAge.age_on(:neptune, input)
+    assert_in_delta 0.35, age, 0.005
+  end
+
+  test "invalid planet causes error" do
+    input = 680_804_807
+    assert SpaceAge.age_on(:sun, input) == {:error, "not a planet"}
+  end
+end

elixir/space-age/test/test_helper.exs

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