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Learn moreUse a recursive method to calculate the sum of all integers from 1 to n.
An ArgumentError should be raised if the input is below 1.
def sum n raise ArgumentError('n must be greater than 0') if n < 1 n == 1 ? 1 : n + sum(n - 1) end1 1 def sum n 2 - return 1 if n == 1 # Base case of recursion method - must be defined; otherwise infinite recursion may occur 3 - n + sum(n - 1) 2 + raise ArgumentError('n must be greater than 0') if n < 1 3 + n == 1 ? 1 : n + sum(n - 1) 4 4 end
describe "The function" do it "should sum up to 10 correctly" do Test.assert_equals sum(1), 1 Test.assert_equals sum(2), 3 Test.assert_equals sum(3), 6 Test.assert_equals sum(4), 10 Test.assert_equals sum(5), 15 Test.assert_equals sum(6), 21 Test.assert_equals sum(7), 28 Test.assert_equals sum(8), 36 Test.assert_equals sum(9), 45 Test.assert_equals sum(10), 55 end it "should sum up to larger numbers correctly too" do Test.assert_equals sum(20), 210 Test.assert_equals sum(30), 465 Test.assert_equals sum(40), 820 Test.assert_equals sum(50), 50 * (50 + 1) / 2 end it "should sum up to any number correctly" do 5.times do rand_int = Test.random_number Test.assert_equals sum(rand_int), rand_int * (rand_int + 1) / 2 end end it "should raise an argument error if n < 1" do Test.expect_error(ArgumentError) { sum(0) } Test.expect_error(ArgumentError) { sum(-100) } end end... lines 1 to 19 have been collapsed. expand 1 1 describe "The function" do 2 2 it "should sum up to 10 correctly" do 3 3 Test.assert_equals sum(1), 1 4 4 Test.assert_equals sum(2), 3 5 5 Test.assert_equals sum(3), 6 6 6 Test.assert_equals sum(4), 10 7 7 Test.assert_equals sum(5), 15 8 8 Test.assert_equals sum(6), 21 9 9 Test.assert_equals sum(7), 28 10 10 Test.assert_equals sum(8), 36 11 11 Test.assert_equals sum(9), 45 12 12 Test.assert_equals sum(10), 55 13 13 end 14 14 it "should sum up to larger numbers correctly too" do 15 15 Test.assert_equals sum(20), 210 16 16 Test.assert_equals sum(30), 465 17 17 Test.assert_equals sum(40), 820 18 18 Test.assert_equals sum(50), 50 * (50 + 1) / 2 19 19 end 20 20 it "should sum up to any number correctly" do 21 21 5.times do 22 22 rand_int = Test.random_number 23 23 Test.assert_equals sum(rand_int), rand_int * (rand_int + 1) / 2 24 24 end 25 25 end 26 + it "should raise an argument error if n < 1" do 27 + Test.expect_error(ArgumentError) { sum(0) } 28 + Test.expect_error(ArgumentError) { sum(-100) } 29 + end 26 26 end