CSV & Enumerables Practice

In this exercise, follow the directions below.

The following files have been provided. Note their directory:

• data/athlete_events.csv. This is a CSV file that has the data of Olympians who participated in Olympic events.
• test/csv_practice_test.rb
• lib/csv_practice.rb

Wave 1 focuses on reading tests, and creating methods that read from a CSV, and transform/calculate from it.

The optional Wave 2 focuses on reading tests, and implementing methods with Enumerable methods.

The optional wave focuses on writing tests, and implementing methods with Enumerable methods.

Wave 1: Reading from a CSV and Transforming the Data

get_all_olympic_athletes(filename)

The tests in test/csv_practice_test.rb describe a method named get_all_olympic_athletes(filename).

This method's responsibility is to:

• take in a filename as a parameter. This should be a string, representing a relative path to a CSV file containing Olympic medalist data.
• return an array of Olympic medalists that is described in a given file.
  • Each Olympic medalist (each element in the array) is a hash.
  • Each Olympic medalist hash should have only the following keys (Notice: this is not all of the keys in the CSV file):
    • "ID"
    • "Name"
    • "Height"
    • "Team"
    • "Year"
    • "City"
    • "Sport"
    • "Event"
    • "Medal"

1. Before reading the test file, write down a description of 2 test cases that test the core functionality, and are nominal tests.

2. Read through the tests in test/csv_practice_test.rb.

   • How did we "Assert" and check that the method returns an array of hashes?
   • How did we "Assert" and check that the method returns an array of hashes with the correct keys?
   • How did we "Assert" and check that the method returns an accurate list of Olympic medalists?
   • What nominal tests did we miss?

3. Write down descriptions of 2 edge test cases that aren't in our tests. (Don't write the tests, just come up with your test cases for practice!)

4. TDD the implementation of get_all_olympic_athletes(filename) with the provided tests. (In other words, given the tests have already been written for you, write the method to get all tests to pass.)

   When calling CSV.read, consider what the relative path of the csv file from the file the code is in

total_medals_per_team(olympic_data)

The tests in test/csv_practice_test.rb describe a method named total_medals_per_team(olympic_data).

This method's responsibility is to:

• take in an array of data of olympic athletes. Each element in the array should be a hash representing an Olympic athlete. (In other words, the result of get_all_olympic_athletes)
• return a hash with the details of how many medals every team has achieved.
  • This hash should have a key for every team that has won at least one medal (the key is a string)
  • The value for each key should be an integer
  • A team has achieved a medal if their medal is not "NA"
• This method SHOULD NOT be reading from a CSV file or writing to a CSV file

1. Write descriptions for 2 test cases that test the core functionality, and are nominal tests.
2. Read through the tests in test/csv_practice_test.rb.
   • In the tests, how do we "Arrange" and setup the data of all Olympic athletes?
   • How did we "Assert" and check that the method returns a hash?
   • How did we "Assert" and check that the method returns an accurate hash?
   • What nominal tests did we miss?
3. Write descriptions for 2 edge test cases that aren't in our tests. (Don't write the tests, just come up with your test cases for practice!)
4. TDD the implementation of total_medals_per_team(olympic_data) with the provided tests.

Can total_medals_per_team Use Enumerable Methods?

If your total_medals_per_team method implementation does not use any of these methods, consider how you could refactor your code to use one of them. You are encouraged to discuss this with a classmate

• filter
• count

No need to actually do the refactor right now.

Optional Wave 2: Transforming, Filtering, or Mapping Data from a CSV

get_all_gold_medalists(olympic_data)

The tests in test/csv_practice_test.rb describe a method named get_all_gold_medalists(olympic_data).

This method's responsibility is to:

• take in an array of data of olympic athletes. Each element in the array should be a hash representing an Olympic athletes. (In other words, the result of get_all_olympic_athletes)
• return an array of hashes.
  • Each element in the array should be a hash that contains all of the Olympic medalist information (ID, Name, Team, etc.)
  • The array should only contain athletes who won a Gold medal, or when their Medal value is equal to "Gold"
• This method SHOULD NOT be reading from a CSV file or writing to a CSV file

1. Write descriptions for 2 test cases that test the core functionality, and are nominal tests.
2. Read through the tests in test/csv_practice_test.rb.
   • In the tests, how do we "Arrange" and setup the data of all Olympic athletes?
   • How did we "Assert" and check that the method returns an array of hashes?
   • How did we "Assert" and check that the method returns an accurate list of only gold medalists?
   • What nominal tests did we miss?
3. Write descriptions for 2 edge test cases that aren't in our tests. (Don't write the tests, just come up with your test cases for practice!)
4. TDD the implementation of get_all_gold_medalists(olympic_data) with the provided tests.
5. If your working implementation did not use the method filter, refactor to use filter now.

More Optionals

Pick one of these methods:

1. team_with_most_medals(medal_totals)
   • This method takes in the result of the total_medals_per_team method.
   • This method returns a hash corresponding to the team (country) with the highest number of medals.
     • The hash should have two key-value pairs:
       1. A key "Team" with a value of the team (country)
       2. A key "Count" with a value of the number of medals
2. athlete_height_in_inches(olympic_data)
   • This method takes in the result of the get_all_olympic_athletes method.
   • This method returns a similar list, but for each athlete, their height should be in inches instead of centimeters.

Follow the following process for that method:

1. Come up with 2 test cases that test the core functionality, and are nominal tests.
2. Come up with 2 edge test cases.
3. TDD the implementation.
4. Refactor. If you didn't, consider how you could use map or sort in your solution.