Initial commit: TDD Workshop exercises for participants

- Password Validator kata with starter code and tests
- Shopping Cart kata with starter code and tests
- FizzBuzz reference code (from live demo)
- Setup guide and TDD reference card
- No solutions included (participants implement themselves)

password_validator/README.md

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+# Feature A — Password Validator
+
+## Your goal
+
+Implement `PasswordValidator` using strict TDD. **Do not write any production code before you have a failing test.**
+
+## Rules to implement (in order)
+
+| Step | Rule | Error message |
+|------|------|---------------|
+| 1 | At least 8 characters long | `Must be at least 8 characters long` |
+| 2 | At least one uppercase letter (A–Z) | `Must contain at least one uppercase letter` |
+| 3 | At least one digit (0–9) | `Must contain at least one digit` |
+| 4 | At least one special character (`!@#$%^&*`) | `Must contain at least one special character (!@#$%^&*)` |
+| 5 | No spaces | `Must not contain spaces` |
+| 6 | All errors reported at once (refactor) | — |
+
+## The rhythm — repeat for every rule
+
+```
+1. Uncomment the next test → run → watch it FAIL (Red)
+2. Write the minimum code to make it pass → run → GREEN
+3. Refactor if needed → run → still GREEN
+4. Move to the next test
+```
+
+## Running the tests
+
+```bash
+dart pub get
+dart test
+```
+
+## Files
+
+- `lib/password_validator.dart` — your implementation goes here
+- `test/password_validator_test.dart` — uncomment tests one at a time
+
+## Hint for Step 6 (the refactor insight)
+
+Once all 5 rules pass, you'll likely have 5 separate `if` blocks in `validate()`.
+Think about how to represent each rule as **data** instead of **code**.
+What if each rule were just a function in a list?

password_validator/lib/password_validator.dart

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+// TODO: Implement PasswordValidator using TDD.
+//
+// Rules (implement one at a time, test first!):
+//   1. Must be at least 8 characters long
+//   2. Must contain at least one uppercase letter
+//   3. Must contain at least one digit
+//   4. Must contain at least one special character (!@#$%^&*)
+//   5. Must not contain spaces
+//
+// ValidationResult holds a pass/fail flag AND a list of error messages.
+// Never return a boolean — the caller deserves to know *why* it failed.
+
+class ValidationResult {
+  final bool isValid;
+  final List<String> errors;
+
+  const ValidationResult({required this.isValid, required this.errors});
+}
+
+class PasswordValidator {
+  ValidationResult validate(String password) {
+    // TODO: implement
+    throw UnimplementedError();
+  }
+}

password_validator/pubspec.yaml

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+name: password_validator
+description: TDD Workshop - Feature A
+
+environment:
+  sdk: ^3.0.0
+
+dev_dependencies:
+  test: ^1.25.0

password_validator/test/password_validator_test.dart

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+import 'package:test/test.dart';
+import '../lib/password_validator.dart';
+
+// ============================================================
+//  PASSWORD VALIDATOR — Workshop Starter
+//  Follow Red → Green → Refactor strictly.
+//  Uncomment one test at a time. Make it pass. Then the next.
+// ============================================================
+
+void main() {
+  late PasswordValidator validator;
+
+  setUp(() {
+    validator = PasswordValidator();
+  });
+
+  // ──────────────────────────────────────────────────────────
+  // STEP 1 — Minimum length
+  // A password needs at least 8 characters.
+  // Start here. Everything else builds on a valid-length string.
+  // ──────────────────────────────────────────────────────────
+  group('Minimum length (8 characters)', () {
+    test('rejects a password shorter than 8 characters', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1!xyz');
+      // expect(result.isValid, isFalse);
+      // expect(result.errors, contains('Must be at least 8 characters long'));
+    });
+
+    test('accepts a password that is exactly 8 characters', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1!xyzw');
+      // expect(result.isValid, isTrue);  // assuming other rules pass too
+    });
+
+    test('accepts a password longer than 8 characters', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1!xyzwqr');
+      // expect(result.isValid, isTrue);
+    });
+  });
+
+  // ──────────────────────────────────────────────────────────
+  // STEP 2 — Uppercase letter
+  // At least one A–Z character must be present.
+  // ──────────────────────────────────────────────────────────
+  group('Uppercase letter required', () {
+    test('rejects a password with no uppercase letters', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('ab1!xyzw');
+      // expect(result.isValid, isFalse);
+      // expect(result.errors, contains('Must contain at least one uppercase letter'));
+    });
+
+    test('accepts a password with at least one uppercase letter', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1!xyzw');
+      // expect(result.isValid, isTrue);
+    });
+  });
+
+  // ──────────────────────────────────────────────────────────
+  // STEP 3 — Digit required
+  // At least one 0–9 character must be present.
+  // ──────────────────────────────────────────────────────────
+  group('Digit required', () {
+    test('rejects a password with no digits', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab!!xyzw');
+      // expect(result.isValid, isFalse);
+      // expect(result.errors, contains('Must contain at least one digit'));
+    });
+
+    test('accepts a password with at least one digit', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1!xyzw');
+      // expect(result.isValid, isTrue);
+    });
+  });
+
+  // ──────────────────────────────────────────────────────────
+  // STEP 4 — Special character required
+  // At least one of: ! @ # $ % ^ & *
+  // ──────────────────────────────────────────────────────────
+  group('Special character required', () {
+    test('rejects a password with no special characters', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1xxxyw');
+      // expect(result.isValid, isFalse);
+      // expect(result.errors, contains('Must contain at least one special character (!@#\$%^&*)'));
+    });
+
+    test('accepts a password with at least one special character', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1!xyzw');
+      // expect(result.isValid, isTrue);
+    });
+  });
+
+  // ──────────────────────────────────────────────────────────
+  // STEP 5 — No spaces allowed
+  // ──────────────────────────────────────────────────────────
+  group('No spaces allowed', () {
+    test('rejects a password that contains a space', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1! xyz');
+      // expect(result.isValid, isFalse);
+      // expect(result.errors, contains('Must not contain spaces'));
+    });
+
+    test('accepts a password with no spaces', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Ab1!xyzw');
+      // expect(result.isValid, isTrue);
+    });
+  });
+
+  // ──────────────────────────────────────────────────────────
+  // STEP 6 — Multiple errors reported at once
+  // The validator collects ALL failures, not just the first.
+  // This is the refactor insight: rules should be independent.
+  // ──────────────────────────────────────────────────────────
+  group('Multiple errors reported together', () {
+    test('reports all failures for a completely invalid password', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('bad');
+      // expect(result.isValid, isFalse);
+      // expect(result.errors.length, equals(4)); // length, uppercase, digit, special char
+    });
+
+    test('a fully valid password has no errors', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('MyP@ssw0rd');
+      // expect(result.isValid, isTrue);
+      // expect(result.errors, isEmpty);
+    });
+  });
+
+  // ──────────────────────────────────────────────────────────
+  // BONUS — Edge cases (if you finish early)
+  // ──────────────────────────────────────────────────────────
+  group('Edge cases', () {
+    test('empty string is invalid and reports the length error', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('');
+      // expect(result.isValid, isFalse);
+      // expect(result.errors, contains('Must be at least 8 characters long'));
+    });
+
+    test('exactly the minimum: 8 chars, all rules satisfied', () {
+      // TODO: uncomment when ready
+      // final result = validator.validate('Aa1!aaaa');
+      // expect(result.isValid, isTrue);
+      // expect(result.errors, isEmpty);
+    });
+  });
+}