https://github.com/sanjibroy360/string-calculator-tdd
A simple string calculator that can add numbers from a given string input with customizable delimiters and validation options.
https://github.com/sanjibroy360/string-calculator-tdd
jest object-oriented-programming oop-typescript string-calculator string-calculator-kata tdd-typescript test-driven-development typescript
Last synced: about 2 months ago
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A simple string calculator that can add numbers from a given string input with customizable delimiters and validation options.
- Host: GitHub
- URL: https://github.com/sanjibroy360/string-calculator-tdd
- Owner: sanjibroy360
- Created: 2025-03-27T09:08:27.000Z (about 1 year ago)
- Default Branch: master
- Last Pushed: 2025-03-29T02:40:28.000Z (about 1 year ago)
- Last Synced: 2025-03-29T03:26:19.816Z (about 1 year ago)
- Topics: jest, object-oriented-programming, oop-typescript, string-calculator, string-calculator-kata, tdd-typescript, test-driven-development, typescript
- Language: TypeScript
- Homepage: https://osherove.com/tdd-kata-1/
- Size: 57.6 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
String Calculator
A simple string calculator that can add numbers from a given string input with customizable delimiters and validation options.
## Implementation Approach
The calculator is implemented using two classes:
### 1. `Calculator`
- Handles basic addition logic.
- Ensures numbers larger than the allowed maximum are ignored.
- Throws errors for negative numbers if required.
### 2. `StringCalculator` (Extends `Calculator`)
- Parses input strings and extracts numbers.
- Supports custom delimiters, multi-character delimiters, and multiple delimiters.
- Converts input into a format suitable for `Calculator` to process.
### Test-Driven Development (TDD) Approach
I followed the TDD methodology by first writing failing test cases before implementing the functionality. Each feature is built incrementally, ensuring all tests passed before moving to the next. I have completed all the steps of [TDD Kata 1](https://osherove.com/tdd-kata-1/).
## Usage
```typescript
const calculator = new StringCalculator();
const result = calculator.add("1,2,3"); // Returns 6
console.log(result); // 6
```
## Features
### 1. Supports adding numbers from a comma-separated string
```typescript
calculator.add("1,2"); // Returns 3
```
### 2. Handles empty string and single-digit string
```typescript
calculator.add(""); // Returns 0
calculator.add("5"); // Returns 5
```
### 3. Handles an unknown amount of numbers
```typescript
calculator.add("1,2,3,4,5"); // Returns 15
```
### 4. Supports newline (`\n`) as a delimiter
```typescript
calculator.add("1\n2,3"); // Returns 6
```
### 5. Allows custom delimiters
You can define a custom delimiter by specifying it at the beginning of the string using the pattern:
`//[delimiter]\n[numbers…]`
```typescript
calculator.add("//;\n1;2"); // Returns 3
```
### 6. Throws an exception for negative numbers
```typescript
calculator.add("1,-2,3"); // Throws "negative numbers not allowed -2"
calculator.add("-1,-2,-3"); // Throws "negative numbers not allowed -1,-2,-3"
```
### 7. Ignores numbers greater than a specified limit (default: 1000)
```typescript
calculator.add("2,1001"); // Returns 2 (1001 is ignored)
```
### 8. Supports multiple custom delimiters, including delimiters of any length
```typescript
calculator.add("//[***]\n1***2***3"); // Returns 6
calculator.add("//[*][%]\n1*2%3"); // Returns 6
calculator.add("//[***][%%]\n1***2%%3"); // Returns 6
```
## Customizable Options
### 1. Allow Only Positive Numbers
By default, negative numbers are not allowed. If a negative number is found, an error will be thrown.
```typescript
calculator.add("-9"); // Throws "negative numbers not allowed -9"
calculator.add("1,2,-3"); // Throws "negative numbers not allowed -3"
```
To allow negative numbers, set allowOnlyPositiveNumbers to false:
```typescript
calculator.add("1,2,-3", false); // Returns 0 (default sum behavior)
```
### 2. Ignore Numbers Larger than a Certain Limit
By default, numbers larger than 1000 are ignored.
```typescript
calculator.add("1,1001,2"); // Returns 3 (1001 is ignored)
calculator.add("1001"); // Returns 0
```
You can change this limit by setting maxAllowedNumber:
```typescript
calculator.add("1,2000,2", true, 2000); // Returns 2003 (2000 is now included)
```
### 3. Custom Delimiters
You can define a custom delimiter by specifying it at the beginning of the string in the format: `"//[delimiter]\n[numbers…]"`
```typescript
calculator.add("//;\n1;2"); // Returns 3 (using `;` as a delimiter)
```
### 4. Multi-character Delimiters
You can use a delimiter of any length.
```typescript
calculator.add("//[***]\n1***2***3"); // Returns 6
```
### 5. Multiple Delimiters
You can define multiple custom delimiters of any length.
```typescript
calculator.add("//[*][%]\n1*2%3"); // Returns 6
calculator.add("//[***][%%]\n1***2%%3"); // Returns 6
```