Pretty JSON Output in Jest

When debugging tests, especially those involving complex data structures like JSON, default Jest output can be difficult to parse. This challenge asks you to create a helper function that formats JSON data in a "pretty" (human-readable) way, making it easier to inspect within your Jest test reports.

Problem Description

You need to implement a TypeScript function named prettyPrintJson that takes a JavaScript object or array and returns a nicely formatted JSON string. This function will be used within Jest tests to improve the readability of assertion failures or console.log outputs during debugging.

Key Requirements:

• The function should accept any valid JavaScript object or array that can be serialized to JSON.
• The output JSON string should be indented with a specified number of spaces for each level of nesting.
• The function should handle nested objects and arrays correctly.
• The function should be written in TypeScript.

Expected Behavior:

• Given an input object, it should return a string representing that object in pretty-printed JSON format.
• Given an input array, it should return a string representing that array in pretty-printed JSON format.

Edge Cases to Consider:

• Empty objects {} and arrays [].
• Objects with null or undefined values (though undefined properties are typically omitted in JSON stringification).
• Deeply nested structures.

Examples

Example 1:

Input:
{
  name: "Hone",
  role: "AI Coding Mentor",
  skills: ["TypeScript", "JavaScript", "Problem Solving"],
  details: {
    version: 1.0,
    active: true
  }
}

Output:
{
  "name": "Hone",
  "role": "AI Coding Mentor",
  "skills": [
    "TypeScript",
    "JavaScript",
    "Problem Solving"
  ],
  "details": {
    "version": 1,
    "active": true
  }
}

Explanation: The input object is converted to a JSON string with an indentation of 2 spaces, making its structure clear.

Example 2:

Input:
[
  { id: 1, value: "apple" },
  { id: 2, value: "banana" }
]

Output:
[
  {
    "id": 1,
    "value": "apple"
  },
  {
    "id": 2,
    "value": "banana"
  }
]

Explanation: An array of objects is also pretty-printed with proper indentation.

Example 3:

Input: {}
Output: {}

Explanation: An empty object is returned as an empty JSON object string.

Example 4:

Input: []
Output: []

Explanation: An empty array is returned as an empty JSON array string.

Constraints

• The indentation level should be configurable, defaulting to 2 spaces if not specified.
• The function should be efficient enough for typical Jest test runs.
• The input will always be a valid JavaScript object or array.

Notes

Consider using built-in JavaScript methods for JSON manipulation. Think about how you can achieve the indentation and formatting requirements. This function is intended to complement Jest's built-in capabilities for assertion messages.