Hello!

26 | 27 |

This lab teaches basic Ruby function syntax.

28 | 29 |

Open a terminal in this directory

30 | 31 |

cd 00_hello
 32 |

33 | 34 |

This directory is the starting point for this exercise. It contains a spec file and a ruby file to (eventually) make the specs pass.

35 | 36 |

Run the test

37 | 38 |

rake
 39 |

40 | 41 |

Watch it fail

42 | 43 |

you should see an error like this:

44 | 45 |

the hello function
 46 |   says hello (FAILED - 1)
 47 | 
 48 | Failures:
 49 | 
 50 |   1) the hello function says hello
 51 |      Failure/Error: expect(hello).to eq("Hello!")
 52 |      NameError:
 53 |        undefined local variable or method `hello' for #<RSpec::Core::ExampleGroup::Nested_1:0x000001009b8808>
 54 |      # ./hello/hello_spec.rb:5:in `block (2 levels) in <top (required)>'
 55 |

56 | 57 |

Create the hello function

58 | 59 |

Fix this by opening hello.rb and creating an empty function:

60 | 61 |

def hello
 62 | end
 63 |

64 | 65 |

Save it. Run the test again.

66 | 67 |

Watch it fail

68 | 69 |

Now you should see an error like this:

70 | 71 |

the hello function
 72 |   says hello (FAILED - 1)
 73 | 
 74 | Failures:
 75 | 
 76 |   1) the hello function says hello
 77 |      Failure/Error: expect(hello).to eq("Hello!")
 78 |        expected: "Hello!"
 79 |             got: nil (compared using ==)
 80 |      # ./hello/hello_spec.rb:5:in `block (2 levels) in <top (required)>'
 81 |

82 | 83 |

This means that while it found the file, and it found the function, it's not returning anything! ("nil" is the Ruby way of saying "not anything".)

84 | 85 |

Make it return something

86 | 87 |

Inside the "hello" function, put a single line containing a string that is not "Hello!". (Here we are simulating you making an honest mistake, so we can see what the error message looks like.)

88 | 89 |

def hello
 90 |   "whuh?"
 91 | end
 92 |

93 | 94 |

Save it. Run the test again.

95 | 96 |

Watch it fail

97 | 98 |

Now you should see an error like this:

99 | 100 |

1) the hello function says hello
101 |    Failure/Error: expect(hello).to eq("Hello!")
102 |      expected: "Hello!"
103 |           got: "whuh?" (compared using ==)
104 |    # ./hello/hello_spec.rb:5:in `block (2 levels) in <top (required)>'
105 |

106 | 107 |

Correct this by changing "whuh?" to "Hello!". Save it. Run the test again.

108 | 109 |

Watch it pass!

110 | 111 |

Hooray! Finally! It works!

112 | 113 |

Give yourself a high five

114 | 115 |

Also, sing a song and do a little dance.

116 | 117 |

And then...

118 | 119 |

Fix the next failure! :-)

120 | 121 |

the hello function
122 |   says hello
123 | 
124 | the greet function
125 |   says hello to someone (FAILED - 1)
126 |

127 | 128 |

In order to get the next test to pass, your function will need to accept an argument.

129 | 130 |

def greet(who)
131 |   "Hello, #{who}!"
132 | end
133 |

134 |

135 |

136 |

Tests

137 | hello_spec.rb 138 |

require "hello"
139 | 
140 | describe "the hello function" do
141 |   it "says hello" do
142 |     expect(hello).to eq("Hello!")
143 |   end
144 | end
145 | 
146 | describe "the greet function" do
147 |   it "says hello to someone" do
148 |     expect(greet("Alice")).to eq("Hello, Alice!")
149 |   end
150 | 
151 |   it "says hello to someone else" do
152 |     expect(greet("Bob")).to eq("Hello, Bob!")
153 |   end
154 | end

155 |

156 |

157 |

temperature

Topics:

26 | 27 |

functions
floating-point math

31 | 32 | 33 |

Hints

34 | 35 |

Remember that one degree fahrenheit is 5/9 of one degree celsius, and that the freezing point of water is 0 degrees celsius but 32 degrees fahrenheit.

36 | 37 |

In integer math, there are no fractions. So if you are using integer literals, you will be using integer math, which means, for example...

38 | 39 |

1 / 2 => 0

40 | 41 |

In floating point math, there are fractions. So...

42 | 43 |

1.0 / 2.0 => 0.5

44 |

45 |

46 |

Tests

47 | temperature_spec.rb 48 |

 49 | require "temperature"
 50 | 
 51 | describe "temperature conversion functions" do
 52 | 
 53 |   describe "#ftoc" do
 54 | 
 55 |     it "converts freezing temperature" do
 56 |       expect(ftoc(32)).to eq(0)
 57 |     end
 58 | 
 59 |     it "converts boiling temperature" do
 60 |       expect(ftoc(212)).to eq(100)
 61 |     end
 62 | 
 63 |     it "converts body temperature" do
 64 |       expect(ftoc(98.6)).to eq(37)
 65 |     end
 66 | 
 67 |     it "converts arbitrary temperature" do
 68 |       expect(ftoc(68)).to eq(20)
 69 |     end
 70 | 
 71 |   end
 72 | 
 73 |   describe "#ctof" do
 74 | 
 75 |     it "converts freezing temperature" do
 76 |       expect(ctof(0)).to eq(32)
 77 |     end
 78 | 
 79 |     it "converts boiling temperature" do
 80 |       expect(ctof(100)).to eq(212)
 81 |     end
 82 | 
 83 |     it "converts arbitrary temperature" do
 84 |       expect(ctof(20)).to eq(68)
 85 |     end
 86 | 
 87 |     it "converts body temperature" do
 88 |       expect(ctof(37)).to be_within(0.1).of(98.6)
 89 |       # Why do we need to use be_within?
 90 |       # See http://www.ruby-forum.com/topic/169330
 91 |       # and http://en.wikipedia.org/wiki/IEEE_754-2008
 92 |       # and http://en.wikipedia.org/wiki/Double_precision_floating-point_format
 93 |       # Also, try "puts 0.5 - 0.4 - 0.1" -- pretty crazy, right?
 94 |     end
 95 | 
 96 |   end
 97 | 
 98 | end

99 |

100 |

101 |

calculator

Topics

26 | 27 |

functions
math
arrays
iterating/looping

33 | 34 | 35 |

Calculator

36 | 37 |

you will build a simple calculator script with the following methods:

38 | 39 |

add takes two parameters and adds them

40 | 41 |

subtract takes two parameters and subtracts the second from the first

42 | 43 |

sum takes an array of parameters and adds them all together

44 | 45 |

Warning

46 | 47 |

You may not have enough knowledge yet to complete sum. You will probably 48 | need to use loops (e.g. while) or iterators (e.g. each) to 49 | get the tests to pass.

50 | 51 |

Bonus

52 | 53 |

There are also some bonus exercises for when you finish the regular ones. The bonus round will help teach you test-driven development, not simply test-guided learning.

54 | 55 |

Your mission, should you choose to accept it, is to write tests for three new methods:

56 | 57 |

multiply which multiplies two numbers together
power which raises one number to the power of another number
[factorial](http://en.wikipedia.org/wiki/Factorial) (check Wikipedia if you forgot your high school math).

62 | 63 |

64 |

65 |

Tests

66 | calculator_spec.rb 67 |

 68 | require "calculator"
 69 | 
 70 | describe "add" do
 71 |   it "adds 0 and 0" do
 72 |     expect(add(0,0)).to eq(0)
 73 |   end
 74 | 
 75 |   it "adds 2 and 2" do
 76 |     expect(add(2,2)).to eq(4)
 77 |   end
 78 | 
 79 |   it "adds positive numbers" do
 80 |     expect(add(2,6)).to eq(8)
 81 |   end
 82 | end
 83 | 
 84 | describe "subtract" do
 85 |   it "subtracts numbers" do
 86 |     expect(subtract(10,4)).to eq(6)
 87 |   end
 88 | end
 89 | 
 90 | describe "sum" do
 91 |   it "computes the sum of an empty array" do
 92 |     expect(sum([])).to eq(0)
 93 |   end
 94 | 
 95 |   it "computes the sum of an array of one number" do
 96 |     expect(sum([7])).to eq(7)
 97 |   end
 98 | 
 99 |   it "computes the sum of an array of two numbers" do
100 |     expect(sum([7,11])).to eq(18)
101 |   end
102 | 
103 |   it "computes the sum of an array of many numbers" do
104 |     expect(sum([1,3,5,7,9])).to eq(25)
105 |   end
106 | end
107 | 
108 | # Extra Credit Test-Driving Bonus:
109 | # once the above tests pass,
110 | # write tests and code for the following:
111 | 
112 | describe "#multiply" do
113 | 
114 |   it "multiplies two numbers"
115 | 
116 |   it "multiplies several numbers"
117 | 
118 | end
119 | 
120 | describe "#power" do
121 |   it "raises one number to the power of another number"
122 | end
123 | 
124 | # http://en.wikipedia.org/wiki/Factorial
125 | describe "#factorial" do
126 |   it "computes the factorial of 0"
127 |   it "computes the factorial of 1"
128 |   it "computes the factorial of 2"
129 |   it "computes the factorial of 5"
130 |   it "computes the factorial of 10"
131 | end

132 |

133 |

134 |

simon_says

Simon Says

26 | 27 |

Topics

28 | 29 |

functions
strings
default parameter values

34 | 35 | 36 |

Hints

37 | 38 |

When you make the second repeat test pass, you might break the first

39 |

40 |

41 |

Tests

42 | simon_says_spec.rb 43 |

 44 | require "simon_says"
 45 | 
 46 | describe "Simon says" do
 47 |   describe "echo" do
 48 |     it "should echo hello" do
 49 |       expect(echo("hello")).to eq("hello")
 50 |     end
 51 | 
 52 |     it "should echo bye" do
 53 |       expect(echo("bye")).to eq("bye")
 54 |     end
 55 |   end
 56 | 
 57 |   describe "shout" do
 58 |     it "should shout hello" do
 59 |       expect(shout("hello")).to eq("HELLO")
 60 |     end
 61 | 
 62 |     it "should shout multiple words" do
 63 |       expect(shout("hello world")).to eq("HELLO WORLD")
 64 |     end
 65 |   end
 66 | 
 67 |   describe "repeat" do
 68 |     it "should repeat" do
 69 |       expect(repeat("hello")).to eq("hello hello")
 70 |     end
 71 | 
 72 |     # Wait a second! How can you make the "repeat" method
 73 |     # take one *or* two arguments?
 74 |     #
 75 |     # Hint: *default values*
 76 |     it "should repeat a number of times" do
 77 |       expect(repeat("hello", 3)).to eq("hello hello hello")
 78 |     end
 79 |   end
 80 | 
 81 |   describe "start_of_word" do
 82 |     it "returns the first letter" do
 83 |       expect(start_of_word("hello", 1)).to eq("h")
 84 |     end
 85 | 
 86 |     it "returns the first two letters" do
 87 |       expect(start_of_word("Bob", 2)).to eq("Bo")
 88 |     end
 89 | 
 90 |     it "returns the first several letters" do
 91 |       s = "abcdefg"
 92 |       expect(start_of_word(s, 1)).to eq("a")
 93 |       expect(start_of_word(s, 2)).to eq("ab")
 94 |       expect(start_of_word(s, 3)).to eq("abc")
 95 |     end
 96 |   end
 97 | 
 98 |   describe "first_word" do
 99 |     it "tells us the first word of 'Hello World' is 'Hello'" do
100 |       expect(first_word("Hello World")).to eq("Hello")
101 |     end
102 | 
103 |     it "tells us the first word of 'oh dear' is 'oh'" do
104 |       expect(first_word("oh dear")).to eq("oh")
105 |     end
106 |   end
107 | 
108 |   describe "titleize" do
109 |     it "capitalizes a word" do
110 |       expect(titleize("jaws")).to eq("Jaws")
111 |     end
112 | 
113 |     it "capitalizes every word (aka title case)" do
114 |       expect(titleize("david copperfield")).to eq("David Copperfield")
115 |     end
116 | 
117 |     it "doesn't capitalize 'little words' in a title" do
118 |       expect(titleize("war and peace")).to eq("War and Peace")
119 |     end
120 | 
121 |     it "does capitalize 'little words' at the start of a title" do
122 |       expect(titleize("the bridge over the river kwai")).to eq("The Bridge over the River Kwai")
123 |     end
124 |   end
125 | 
126 | end

127 |

128 |

129 |

pig_latin

Topics

26 | 27 |

modules
strings

31 | 32 | 33 |

Pig Latin

34 | 35 |

Pig Latin is a made-up children's language that's intended to be confusing. It obeys a few simple rules (below) but when it's spoken quickly it's really difficult for non-children (and non-native speakers) to understand.

36 | 37 |

Rule 1: If a word begins with a vowel sound, add an "ay" sound to the end of the word.

38 | 39 |

Rule 2: If a word begins with a consonant sound, move it to the end of the word, and then add an "ay" sound to the end of the word.

40 | 41 |

(There are a few more rules for edge cases, and there are regional variants too, but that should be enough to understand the tests.)

42 | 43 |

See http://en.wikipedia.org/wiki/Pig_latin for more details.

44 |

45 |

46 |

Tests

47 | pig_latin_spec.rb 48 |

 49 | require "pig_latin"
 50 | 
 51 | describe "#translate" do
 52 | 
 53 |   it "translates a word beginning with a vowel" do
 54 |     s = translate("apple")
 55 |     expect(s).to eq("appleay")
 56 |   end
 57 | 
 58 |   it "translates a word beginning with a consonant" do
 59 |     s = translate("banana")
 60 |     expect(s).to eq("ananabay")
 61 |   end
 62 | 
 63 |   it "translates a word beginning with two consonants" do
 64 |     s = translate("cherry")
 65 |     expect(s).to eq("errychay")
 66 |   end
 67 | 
 68 |   it "translates two words" do
 69 |     s = translate("eat pie")
 70 |     expect(s).to eq("eatay iepay")
 71 |   end
 72 | 
 73 |   it "translates a word beginning with three consonants" do
 74 |     expect(translate("three")).to eq("eethray")
 75 |   end
 76 | 
 77 |   it "counts 'sch' as a single phoneme" do
 78 |     s = translate("school")
 79 |     expect(s).to eq("oolschay")
 80 |   end
 81 | 
 82 |   it "counts 'qu' as a single phoneme" do
 83 |     s = translate("quiet")
 84 |     expect(s).to eq("ietquay")
 85 |   end
 86 | 
 87 |   it "counts 'qu' as a consonant even when it's preceded by a consonant" do
 88 |     s = translate("square")
 89 |     expect(s).to eq("aresquay")
 90 |   end
 91 | 
 92 |   it "translates many words" do
 93 |     s = translate("the quick brown fox")
 94 |     expect(s).to eq("ethay ickquay ownbray oxfay")
 95 |   end
 96 | 
 97 |   # Test-driving bonus:
 98 |   # * write a test asserting that capitalized words are still capitalized (but with a different initial capital letter, of course)
 99 |   # * retain the punctuation from the original phrase
100 | 
101 | end

102 |

103 |

104 |

the home of test-first teaching

hello

Hello!

Open a terminal in this directory

Run the test

Watch it fail

Create the hello function

Watch it fail

Make it return something

Watch it fail

Watch it pass!

Give yourself a high five

And then...

Tests

the home of test-first teaching

temperature

Topics:

Hints

Tests

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calculator

Topics

Calculator

Warning

Bonus

Tests

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simon_says

Simon Says

Topics

Hints

Tests

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pig_latin

Topics

Pig Latin

Tests

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book_titles

Book Titles

Topics

Notes

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timer

Topics

Timer

Tests