HackerRank Day 27: Testing 30 days of code solution

Today we are going to solve HackerRank Day 27: Testing 30 days of code solutions in Java & Python.

Task

This problem is about unit testing. Your company needs a function that meets the following requirements:

• For a given array of n integers, the function returns the index of the element with the minimum value in the array. If there is more than one element with the minimum value, it returns the smallest one.
• If an empty array is passed to the function, it raises an exception. A colleague has written this method. The implementation in Python is listed below. Implementations in other languages can be found in the code template.

def minimum_index(seq):
    if len(seq) == 0:
        raise ValueError("Cannot get the minimum value index from an empty sequence")
    min_idx = 0
    for i in range(1, len(seq)):
        if a[i] < a[min_idx]:
            min_idx = i
    return min_idx

A coworker has prepared functions that will perform the tests and validate return values. Finish the implementation of  classes to provide data and expected results for the tests.

Complete the following methods.

In the class TestDataEmptyArray:

• get_array() returns an empty array

In the class TestDataUniqueValues:

• get_array() returns an array of size at least 2 with all unique elements
• get_expected_result() returns the expected minimum value index for this array

In the class TestDataExactlyTwoDifferentMinimums:

• get_array() returns an array where the minimum value occurs at exactly 2 indices
• get_expected_result() returns the expected index

Take a look at the code template to see the exact implementation of functions that your colleague already implemented.

Note: The arrays are indexed from 0.

HackerRank Day 27: Testing 30 days of code solution

Testing HackerRank Solution in Java

import java.util.*;

public class Solution {
    public static int minimum_index(int[] seq) {
        if (seq.length == 0) {
            throw new IllegalArgumentException("Cannot get the minimum value index from an empty sequence");
        }
        int min_idx = 0;
        for (int i = 1; i < seq.length; ++i) {
            if (seq[i] < seq[min_idx]) {
                min_idx = i;
            }
        }
        return min_idx;
    }
    static class TestDataEmptyArray {
        public static int[] get_array() {
        int arr[]={};
        return arr;
        }
    }
    static class TestDataUniqueValues {
        public static int[] get_array() {
            // complete this function
            int arr[]={1,2,3,4,5};
        return arr;
        }
        public static int get_expected_result() {
            // complete this function
            return 0;
        }
    }
    static class TestDataExactlyTwoDifferentMinimums {
        public static int[] get_array() {
            // complete this function
            int arr[]={1,3,1};
        return arr;
        }
        public static int get_expected_result() {
            // complete this function
            return 0;
        }
    }
 public static void TestWithEmptyArray() {
        try {
            int[] seq = TestDataEmptyArray.get_array();
            int result = minimum_index(seq);
        } catch (IllegalArgumentException e) {
            return;
        }
        throw new AssertionError("Exception wasn't thrown as expected");
    }
    public static void TestWithUniqueValues() {
        int[] seq = TestDataUniqueValues.get_array();
        if (seq.length < 2) {
            throw new AssertionError("less than 2 elements in the array");
        }
        Integer[] tmp = new Integer[seq.length];
        for (int i = 0; i < seq.length; ++i) {
            tmp[i] = Integer.valueOf(seq[i]);
        }
        if (!((new LinkedHashSet<Integer>(Arrays.asList(tmp))).size() == seq.length)) {
            throw new AssertionError("not all values are unique");
        }
        int expected_result = TestDataUniqueValues.get_expected_result();
        int result = minimum_index(seq);
        if (result != expected_result) {
            throw new AssertionError("result is different than the expected result");
        }
    }
    public static void TestWithExactlyTwoDifferentMinimums() {
        int[] seq = TestDataExactlyTwoDifferentMinimums.get_array();
        if (seq.length < 2) {
            throw new AssertionError("less than 2 elements in the array");
        }
        int[] tmp = seq.clone();
        Arrays.sort(tmp);
        if (!(tmp[0] == tmp[1] && (tmp.length == 2 || tmp[1] < tmp[2]))) {
            throw new AssertionError("there are not exactly two minimums in the array");
        }
        int expected_result = TestDataExactlyTwoDifferentMinimums.get_expected_result();
        int result = minimum_index(seq);
        if (result != expected_result) {
            throw new AssertionError("result is different than the expected result");
        }
    }
    public static void main(String[] args) {
        TestWithEmptyArray();
        TestWithUniqueValues();
        TestWithExactlyTwoDifferentMinimums();
        System.out.println("OK");
    }
}

Testing HackerRank Solution in Python 3

def minimum_index(seq):
    if len(seq) == 0:
        raise ValueError("Cannot get the minimum value index from an empty sequence")
    min_idx = 0
    for i in range(1, len(seq)):
        if seq[i] < seq[min_idx]:
            min_idx = i
    return min_idx
class TestDataEmptyArray(object):
    
    @staticmethod
    def get_array():
        return list()

class TestDataUniqueValues(object):

    @staticmethod
    def get_array():
        return [7,9,1,2,-7,10,22]

    @staticmethod
    def get_expected_result():
        return 4

class TestDataExactlyTwoDifferentMinimums(object):

    @staticmethod
    def get_array():
        return [7,9,1,2,-7,10,22,-7]

    @staticmethod
    def get_expected_result():
        return 4


def TestWithEmptyArray():
    try:
        seq = TestDataEmptyArray.get_array()
        result = minimum_index(seq)
    except ValueError as e:
        pass
    else:
        assert False


def TestWithUniqueValues():
    seq = TestDataUniqueValues.get_array()
    assert len(seq) >= 2

    assert len(list(set(seq))) == len(seq)

    expected_result = TestDataUniqueValues.get_expected_result()
    result = minimum_index(seq)
    assert result == expected_result


def TestiWithExactyTwoDifferentMinimums():
    seq = TestDataExactlyTwoDifferentMinimums.get_array()
    assert len(seq) >= 2
    tmp = sorted(seq)
    assert tmp[0] == tmp[1] and (len(tmp) == 2 or tmp[1] < tmp[2])

    expected_result = TestDataExactlyTwoDifferentMinimums.get_expected_result()
    result = minimum_index(seq)
    assert result == expected_result

TestWithEmptyArray()
TestWithUniqueValues()
TestiWithExactyTwoDifferentMinimums()
print("OK")

NEXT: HackerRank Day 28: RegEx Patterns and Intro to Database 30 days of code solution

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