[Part 3]Control Flow and Decision Making in TypeScript for QA Scripts

Introduction

Control flow structures allow test automation scripts to make decisions, repeat tasks, and handle different test cases dynamically. This module covers conditional statements, loops, and type-safe assertions to create robust TypeScript test scripts.

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Lesson 1: Conditional Statements – if, else if, else with Type Guards

Concept:
Conditional statements enable automated tests to branch logic based on specific conditions.

Key Topics:

• Basic if-else Statements: Controlling test execution based on conditions.
• Multiple Conditions: Using else if for handling various test scenarios.
• Type Guards: Ensuring type safety within conditionals.

Example:

let testStatus: string | null = "Passed";
if (testStatus === "Passed") {
    console.log("Test succeeded.");
} else if (testStatus === "Failed") {
    console.log("Test failed. Needs debugging.");
} else {
    console.log("Unknown test status.");
}

Pro Tip: Use TypeScript’s typeof or instanceof for type guards in complex conditionals.

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Lesson 2: Mastering Loops – for, while, for...of, and forEach

Concept:
Loops automate repetitive tasks such as iterating through test cases or dataset validations.

Key Topics:

• for Loop: Iterating a set number of times.
• while Loop: Running until a condition is false.
• for...of Loop: Simplified iteration over arrays.
• forEach Method: Functional iteration over collections.

Example:

let testCases: string[] = ["Login", "Signup", "Checkout"];
for (let test of testCases) {
    console.log(`Running ${test} test...`);
}

Pro Tip: Use forEach() for cleaner, functional-style array iteration in test automation scripts.

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Lesson 3: Boolean Logic and Comparison Operators – Building Type-Safe Assertions

Concept:
Boolean logic allows test scripts to evaluate conditions and execute assertions.

Key Topics:

• Comparison Operators: ===, !==, >, <, >=, <=
• Logical Operators: &&, ||, ! for complex conditions.
• Type-Safe Assertions: Validating expected vs. actual test results.

Example:

let expected: string = "Success";
let actual: string = "Success";
console.assert(expected === actual, "Test result mismatch");

Pro Tip: Use strict equality (===) to avoid unintended type coercion in assertions.

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Conclusion

This module covered JavaScript control flow structures, helping to write dynamic and efficient test automation scripts.

Key Takeaways:

• Conditional statements help automate decision-making in test execution.
• Loops simplify repetitive tasks, making tests more scalable.
• Boolean logic and assertions ensure expected test results.

What’s Next?
In the next module, we will explore Data Structures in TypeScript: Organizing Test Data with Strong Typing, covering arrays, objects, tuples, and enums to store and manage test data efficiently.

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