[Solved] What is wrong with this test code?let(:array) { [] } before { array — Ans: The array is shared and mutated across tests causing unexpected results | Ruby

Ruby - Testing with RSpec and Minitest

What is wrong with this test code?

let(:array) { [] }
before { array << 1 }
it 'has one element' do
  expect(array.size).to eq(1)
end
it 'is empty initially' do
  expect(array).to eq([])
end

Alet does not allow modifying returned objects

Bbefore hook runs after the test examples

CThe array is shared and mutated across tests causing unexpected results

Darray is not defined in before hook

Step-by-Step Solution

Solution:

Step 1: Understand let memoization and mutation
let(:array) returns a new array instance per example, but mutation inside before affects that instance within the example.
Step 2: Analyze test order and mutation effect
Each test example gets a fresh array, but mutation in one example does not affect others. However, if the array is memoized and mutated in a shared context, it can cause unexpected results.
Final Answer:
The array is shared and mutated across tests causing unexpected results -> Option C
Quick Check:
Mutating let objects can cause shared state bugs if not careful [OK]

Quick Trick: Avoid mutating let objects to prevent shared state bugs [OK]

Common Mistakes:

Assuming let returns new object each time
Thinking before runs after tests
Ignoring mutation side effects

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What is wrong with this test code?

Step 1: Understand let memoization and mutation

Step 2: Analyze test order and mutation effect

Final Answer:

Quick Check:

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