Add 'Assigning data' unit

Author: paulgoetze

1_Introduction/3_Assigning_data/solution.rb

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+variable_types = 3
+language = 'Ruby'
+learned = true
+
+puts variable_types
+puts language
+puts learned

1_Introduction/3_Assigning_data/solution_spec.rb

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+require 'rspec'
+
+describe 'Your code' do
+
+  describe do
+    before do
+      allow($stdout).to receive(:puts) {''}
+      allow($stdout).to receive(:p) {''}
+      allow($stdout).to receive(:print) {''}
+    end
+
+    it 'defines a variable "variable_types" with the value 3' do
+      [['solution::code']]
+      expect(!!defined?(variable_types)).to be true
+      expect(variable_types).to eq 3
+    end
+
+    it 'defines a variable "language" with the value \'Ruby\'' do
+      [['solution::code']]
+      expect(!!defined?(language)).to be true
+      expect(language).to eq 'Ruby'
+    end
+
+    it 'defines a variable "learned" with the value true' do
+      [['solution::code']]
+      expect(!!defined?(learned)).to be true
+      expect(learned).to eq true
+    end
+  end
+
+  it 'puts the values of all defined variables to the standard output' do
+    expect($stdout).to receive(:puts).with(3)
+    expect($stdout).to receive(:puts).with('Ruby')
+    expect($stdout).to receive(:puts).with(true)
+    [['solution::code']]
+  end
+end

1_Introduction/3_Assigning_data/task.md

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+# Assigning data
+
+---
+
+*You will learn:*
+- what a variable is
+- three basic Ruby data types
+- how you can assign data to a variable
+- how to receive and use the assigned data again
+
+---
+
+## Variables
+
+Running a programm is all about analyzing and manipulating data.
+If you want to manipulate the same data multiple times, you have to store it
+somewhere and access it when you need it. For this temporary storage of data
+you use data containers, so called *variables*.
+
+The name of a variables is usually underscore-separated downcased words, like:
+
+`title`, `my_name`, `a_very_long_variable_name` (but try to keep it short!)
+
+Variables that are not meant to be changed after they once got a value are
+called *constants* and, by convention, have uppercase names, like `DEFAULT_NAME`.
+
+Ruby is *case sensitive*, so it cares about capitalization of your variable names.
+This means: `my_name` would be another variable than `my_Name`.
+
+## Three basic data types
+
+Now, we want to have a look at three basic data types in Ruby. We will see more
+types later on.
+
+*1. Strings:* A String represents a text or character and can be simply build by
+writing text between two single quotes (*''*) or double quotes (*""*), e.g.
+
+`'This is a string.'`, `'&'` or `"This too :)!"`
+
+*2. Numbers:* Numbers can be build by just typing the number. Ruby uses several
+number classes internally which you don't have to care about for now.
+If you type a number, Ruby does all the work for you and uses the appropriate
+class for the number. For instance, if you type `1` it will give you a *Fixnum*,
+if you type `1.5` it will give you a *Float*.
+
+*3. Booleans:* A Boolean represents a binary state. A Boolean's value can be
+either *true* or *false*. Keep in mind not to put quotes around *true* or *false*
+if you want to create a Boolean, else it would be a String!
+
+## Variable = 'value'
+
+You can assign data to a variable by using the equals sign `=`.
+E.g. `learned = true` assigns the value *true* to the variable *learned*.
+
+## Getting the data of a variable
+
+After assigning a value to a variable you can acces the value again by typing
+the variable's name.
+
+Typing `learned` will give you the value *true* (which is a Boolean, remember?).
+
+Let us now create some variables and print their values:
+
+---
+
+Set the following variables:
+
+`  variable_types`  to the number *3*
+`  language`        to the string *'Ruby'* and
+`  learned`         to the boolean *true*
+
+and print out each variable's value by using the *puts* method!
+
+---