[Crystal] Crystal Hunter

Author: sanderploegsma

crystal/crystal-hunter/HELP.md

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+# Help
+
+## Running the tests
+
+Execute the tests with:
+
+```bash
+$ crystal spec
+```
+
+## Skipped tests
+
+In each test suite all but the first test have been skipped.
+
+Once you get a test passing, you can unskip the next one by changing `pending` to `it`.
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/crystal_hunter.cr` 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 [Crystal track's documentation](https://exercism.org/docs/tracks/crystal)
+- The [Crystal track's programming category on the forum](https://forum.exercism.org/c/programming/crystal)
+- [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.
+
+To get help if you're having trouble, you can use one of the following resources:
+
+- [Crystal API](http://crystal-lang.org/api/)
+- [r/crystal_programming/](https://www.reddit.com/r/crystal_programming/) is the Crystal subreddit.
+- [StackOverflow](https://stackoverflow.com/questions/tagged/crystal-lang) can be used to search for your problem and see if it has been answered already. You can also ask and answer questions.
+- [Crystal Forum](https://forum.crystal-lang.org/) is the official Crystal forum.

crystal/crystal-hunter/HINTS.md

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+# Hints
+
+## General
+
+- Don't worry about how the arguments are _derived_, focus on combining the arguments to return the intended result.
+
+## 1. Define if character gets bonus points
+
+- You can use [the logical _and_ operator][and] to combine arguments for a result.
+
+## 2. Define if character scores
+
+- You can use [the logical _or_ operator][or] to combine arguments for a result.
+
+## 3. Define if character loses
+
+- You can use [the logical _not_ operator][not] to negate an argument for a result.
+
+## 4. Define if character wins
+
+- You can use the previous methods to combine arguments for a result.
+
+[and]: https://crystal-lang.org/reference/latest/syntax_and_semantics/and.html
+[or]: https://crystal-lang.org/reference/latest/syntax_and_semantics/or.html
+[not]: https://crystal-lang.org/reference/latest/syntax_and_semantics/not.html

crystal/crystal-hunter/README.md

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+# Crystal Hunter
+
+Welcome to Crystal Hunter on Exercism's Crystal Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
+
+## Introduction
+
+Crystal has a type known as [`Bool`][bools], it is used to represent the values `true` and `false`.
+
+## Logical operators
+
+Crystal has 3 logical operators (`!`, `||`, `&&`) which are used to combine Bools and make expressions that produce different values.
+
+### And(`&&`)
+
+The [_and_ operator][and] in Crystal is represented by `&&` and returns `true` if both values given are `true` otherwise it returns `false`.
+When using the _and_ operator, one Bool be placed on the right side of the `&&` and another one on the left side.
+
+```crystal
+true && true
+# => true
+
+true && false
+# => false
+```
+
+### Or(`||`)
+
+The [_or_ operator][or] in Crystal is represented by `||` and returns `true` if **at least one** of values given is `true` if both of the values are `false` then it returns `false`.
+When using the _or_ operator one bool should be placed on the right side of the `||` and another one on the left side.
+
+```crystal
+true || true
+# => true
+
+true || false
+# => true
+
+false || false
+# => false
+```
+
+### Not(`!`)
+
+The _not_ operator in Crystal is represented by `!` and returns `true` if the given Bool is `false` and returns `false` if `true` is given.
+When using the _not_ operator one Bool should be placed after the operator (`!`).
+
+```crystal
+!true
+# => false
+
+!false
+# => true
+```
+
+## Using parentheses(`()`)
+
+When working with booleans you can use parentheses to decide which Bools to evaluate first.
+The result can differ depending on how the parentheses are used.
+In Crystal, what is in parentheses is evaluated first.
+
+```crystal
+true && false && false || true
+# => true
+
+true && false && (false || true)
+# => false
+```
+
+Since what is in parentheses is evaluated first, in the following example, the _not_ operator will apply to the expression inside parentheses.
+
+```crystal
+!true && false
+# => false
+
+!(true && false)
+# => true
+```
+
+~~~~exercism/note
+You should only use parentheses when they affect the result, otherwise, should they be omitted.
+~~~~
+
+[bools]: https://crystal-lang.org/reference/latest/syntax_and_semantics/literals/bool.html
+[and]: https://crystal-lang.org/reference/latest/syntax_and_semantics/and.html
+[or]: https://crystal-lang.org/reference/latest/syntax_and_semantics/or.html
+
+## Instructions
+
+You are in process of developing the new highly appreciated game **Crystal Hunter**.
+In the game you are a character that moves around and collects crystals.
+The player wins by picking up all the crystals.
+If the player comes in contact with a bandit, then the player will lose all their crystals and lose the game.
+There is an exception to this rule: the player can have an active power-up that makes them invisible to the bandits.
+
+Your goal is to write some rules that will be used in the game.
+
+## 1. Define if character gets bonus points
+
+In the game, the character will get bonus points if they touch a bandit while having a power-up.
+
+Define the `Rules#bonus_points?` method that takes two arguments (_if the character has an active power-up_ and _if the character is touching a bandit_) and returns a boolean value that tells whether the character will get bonus points or not.
+The method should return `true` only if the character has a power-up active and is touching a bandit, and `false` otherwise.
+
+```Crystal
+Rules.new.bonus_points?(false, true)
+# => false
+```
+
+## 2. Define if character scores
+
+In the game, the player gets points when picking up a crystal or a power-up.
+
+Define the `Rules#score?` method that takes two arguments (_if the character is touching a power-up_ and _if the character is touching a crystal_) and returns a boolean value indicating if the character scored or not.
+The method should return `true` if the character is touching a power-up or a crystal, and return `false` otherwise.
+
+```crystal
+Rules.new.score?(true, true)
+# => true
+```
+
+## 3. Define if character loses
+
+Define the `Rules#lose?` method that takes two arguments (_if the character has a power-up active_ and _if the character is touching a bandit_) and returns a boolean value that indicates if the character loses or not.
+The method should return `true` if the character is touching a bandit and does not have a power-up active, and return `false` otherwise.
+
+```crystal
+Rules.new.lose?(false, true)
+# => true
+```
+
+## 4. Define if character wins
+
+Define the `Rules#win?` method that takes three arguments (_if the character has picked up all of the crystals_, _if the character has a power-up active_, and _if the character is touching a bandit_) and returns a boolean value indicating if the character wins or not.
+The method should return `true` if the character has gathered all crystals and has not lost based on the arguments defined in part 3, and return `false` otherwise.
+
+```crystal
+Rules.new.win?(false, true, false)
+# => false
+```
+
+## Source
+
+### Created by
+
+- @meatball133
+
+### Contributed to by
+
+- @andrerfcsantos
+- @angelikatyborska
+- @glennj
+- @ryanplusplus

crystal/crystal-hunter/spec/crystal_hunter_spec.cr

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+require "spec"
+require "../src/*"
+
+describe Rules do
+  describe "bonus_points?" do
+    it "Character gets bonus points" do
+      Rules.new.bonus_points?(true, true).should be_true
+    end
+
+    it "Character gets no bonus points because no power-up is active" do
+      Rules.new.bonus_points?(false, true).should be_false
+    end
+
+    it "Character gets no bonus points because not touching bandit" do
+      Rules.new.bonus_points?(true, false).should be_false
+    end
+
+    it "Character gets no bonus points because no power-up is active and character is not touching bandit" do
+      Rules.new.bonus_points?(false, false).should be_false
+    end
+  end
+
+  describe "score?" do
+    it "Score when picking up crystal" do
+      Rules.new.score?(true, false).should be_true
+    end
+
+    it "Score when picking up power-up" do
+      Rules.new.score?(false, true).should be_true
+    end
+
+    it "No score when not picking up anything" do
+      Rules.new.score?(false, false).should be_false
+    end
+  end
+
+  describe "lose?" do
+    it "Lose if touching a bandit without a power-up active" do
+      Rules.new.lose?(false, true).should be_true
+    end
+
+    it "Don't lose if touching a bandit with a power-up active" do
+      Rules.new.lose?(true, true).should be_false
+    end
+
+    it "Don't lose if not touching a bandit" do
+      Rules.new.lose?(false, false).should be_false
+    end
+
+    it "Don't lose if powered-up and not touching a bandit" do
+      Rules.new.lose?(true, false).should be_false
+    end
+  end
+
+  describe "win?" do
+    it "Win if all crystals have been picked up" do
+      Rules.new.win?(true, false, false).should be_true
+    end
+
+    it "Don't win if all crystals have been picked up, but touching a bandit" do
+      Rules.new.win?(true, false, true).should be_false
+    end
+
+    it "Win if all crystals have been picked up and touching a bandit with a power-up active" do
+      Rules.new.win?(true, true, true).should be_true
+    end
+  end
+end

crystal/crystal-hunter/src/crystal_hunter.cr

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+class Rules
+  def bonus_points?(power_up_active, touching_bandit)
+    touching_bandit && power_up_active
+  end
+
+  def score?(touching_power_up, touching_crystal)
+    touching_crystal || touching_power_up
+  end
+
+  def lose?(power_up_active, touching_bandit)
+    touching_bandit && !power_up_active
+  end
+
+  def win?(has_picked_up_all_crystals, power_up_active, touching_bandit)
+    !lose?(power_up_active, touching_bandit) && has_picked_up_all_crystals
+  end
+end