REFACTOR: organize tests into groups and add edge cases

test/roman_numerals_test.dart

@@ -1,80 +1,70 @@
-import 'package:tdd_katas/roman_numerals.dart' as roman_numerals;
+import 'package:tdd_katas/roman_numerals.dart';
 import 'package:test/test.dart';
 
 void main() {
-  test('converts 1 to I', () {
+  group('Roman Numerals Conversion', () {
-    expect(roman_numerals.integerToRoman(1), 'I');
+    group('Basic Symbols', () {
+      test('smallest unit', () => expect(integerToRoman(1), 'I'));
+      test('five', () => expect(integerToRoman(5), 'V'));
+      test('ten', () => expect(integerToRoman(10), 'X'));
+      test('fifty', () => expect(integerToRoman(50), 'L'));
+      test('hundred', () => expect(integerToRoman(100), 'C'));
+      test('five hundred', () => expect(integerToRoman(500), 'D'));
+      test('thousand', () => expect(integerToRoman(1000), 'M'));
     });
 
-  test('converts 2 to II', () {
+    group('Subtractive Notation', () {
-    expect(roman_numerals.integerToRoman(2), 'II');
+      test('four (one before five)', () => expect(integerToRoman(4), 'IV'));
+      test('nine (one before ten)', () => expect(integerToRoman(9), 'IX'));
+      test('forty (ten before fifty)', () => expect(integerToRoman(40), 'XL'));
+      test(
+        'ninety (ten before hundred)',
+        () => expect(integerToRoman(90), 'XC'),
+      );
+      test(
+        'four hundred (hundred before five hundred)',
+        () => expect(integerToRoman(400), 'CD'),
+      );
+      test(
+        'nine hundred (hundred before thousand)',
+        () => expect(integerToRoman(900), 'CM'),
+      );
     });
 
-  test('converts 3 to III', () {
+    group('Additive Combinations', () {
-    expect(roman_numerals.integerToRoman(3), 'III');
+      test('two (repeated symbol)', () => expect(integerToRoman(2), 'II'));
+      test(
+        'three (maximum repetition)',
+        () => expect(integerToRoman(3), 'III'),
+      );
+      test('six (additive after five)', () => expect(integerToRoman(6), 'VI'));
+      test(
+        'twenty-seven (multiple symbols)',
+        () => expect(integerToRoman(27), 'XXVII'),
+      );
     });
 
-  test('converts 4 to IV', () {
+    group('Complex Edge Cases', () {
-    expect(roman_numerals.integerToRoman(4), 'IV');
+      test(
+        'forty-nine (combines subtractive symbols)',
+        () => expect(integerToRoman(49), 'XLIX'),
+      );
+      test(
+        'ninety-nine (maximum two-digit complexity)',
+        () => expect(integerToRoman(99), 'XCIX'),
+      );
+      test(
+        'four hundred forty-four (all subtractive positions)',
+        () => expect(integerToRoman(444), 'CDXLIV'),
+      );
+      test(
+        '1994 (year notation stress test)',
+        () => expect(integerToRoman(1994), 'MCMXCIV'),
+      );
+      test(
+        '3999 (maximum valid Roman numeral)',
+        () => expect(integerToRoman(3999), 'MMMCMXCIX'),
+      );
     });
-
-  test('converts 5 to V', () {
-    expect(roman_numerals.integerToRoman(5), 'V');
-  });
-
-  test('converts 6 to VI', () {
-    expect(roman_numerals.integerToRoman(6), 'VI');
-  });
-
-  test('converts 7 to VII', () {
-    expect(roman_numerals.integerToRoman(7), 'VII');
-  });
-
-  test('converts 8 to VIII', () {
-    expect(roman_numerals.integerToRoman(8), 'VIII');
-  });
-
-  test('converts 9 to IX', () {
-    expect(roman_numerals.integerToRoman(9), 'IX');
-  });
-
-  test('converts 10 to X', () {
-    expect(roman_numerals.integerToRoman(10), 'X');
-  });
-
-  test('converts 40 to XL', () {
-    expect(roman_numerals.integerToRoman(40), 'XL');
-  });
-
-  test('converts 49 to XLIX', () {
-    expect(roman_numerals.integerToRoman(49), 'XLIX');
-  });
-
-  test('converts 50 to L', () {
-    expect(roman_numerals.integerToRoman(50), 'L');
-  });
-
-  test('converts 90 to XC', () {
-    expect(roman_numerals.integerToRoman(90), 'XC');
-  });
-
-  test('converts 100 to C', () {
-    expect(roman_numerals.integerToRoman(100), 'C');
-  });
-
-  test('converts 400 to CD', () {
-    expect(roman_numerals.integerToRoman(400), 'CD');
-  });
-
-  test('converts 500 to D', () {
-    expect(roman_numerals.integerToRoman(500), 'D');
-  });
-
-  test('converts 900 to CM', () {
-    expect(roman_numerals.integerToRoman(900), 'CM');
-  });
-
-  test('converts 1000 to M', () {
-    expect(roman_numerals.integerToRoman(1000), 'M');
   });
 }