feature4

feature4

+import re 
+import unittest
+
+class StringCalculator:
+    def add(self, numbers: str) -> int:
+        # Feature 1: Leerer String ergibt 0
+        if not numbers:
+            return 0
+
+        # Vorbereitung für weiter features 
+        if numbers.startswith("//"):
+            delimiter_end_index = numbers.index("\n")
+            delimiter = numbers[2:delimiter_end_index]
+            numbers = numbers[delimiter_end_index + 1:]
+            numbers = numbers.replace(delimiter, ",")
+
+        # Feature 3: Erlaube Zeilenumbrüche als Trenner
+        numbers = numbers.replace("\n", ",")
+
+        # Aufteilen der Zahlen durch Komma
+        number_list = numbers.split(",")
+
+        # Feature 4: Negativzahlen abfangen
+        negatives = []
+        for num in number_list:
+            if num.strip() != "":
+                value = int(num)
+                if value < 0:
+                    negatives.append(value)
+
+        # Exception bei negativen Zahlen
+        if negatives:
+            raise ValueError(f"Negative numbers are not allowed: {', '.join(map(str, negatives))}")
+
+        # Feature 2: Beliebig viele Zahlen summieren
+        return sum(int(n) for n in number_list if n.strip() != "")
+
+
+class TestStringCalculator(unittest.TestCase):
+    """Test suite for the StringCalculator class."""
+
+    def setUp(self):
+        """neue Instanz des StringCalculators vor jedem Test"""
+        self.calculator = StringCalculator()
+
+    def test_empty_string_returns_zero(self):
+        """Feature 1: Leerer String soll 0 ergeben"""
+        self.assertEqual(self.calculator.add(""), 0)
+
+    def test_single_number_returns_value(self):
+        """Ein einzelner Wert soll zurückgegeben werden"""
+        self.assertEqual(self.calculator.add("1"), 1)
+
+    def test_two_numbers_return_sum(self):
+        """Zwei Zahlen sollen summiert werden"""
+        self.assertEqual(self.calculator.add("1,2"), 3)
+
+    def test_add_multiple_numbers(self):
+        """Feature 2: Mehrere Zahlen summieren"""
+        self.assertEqual(self.calculator.add("1,2,3,4,5"), 15)
+
+    def test_add_numbers_with_newlines(self):
+        """Feature 3: Zeilenumbrüche als Trennzeichen"""
+        self.assertEqual(self.calculator.add("1\n2\n3"), 6)
+
+    def test_add_negative_numbers(self):
+        """Feature 4: Negative Zahlen sollen Fehler werfen"""
+        with self.assertRaises(ValueError) as e:
+            self.calculator.add("-1,2,-3")
+        self.assertEqual(str(e.exception), "Negative numbers are not allowed: -1, -3")
+
+
+
+if __name__ == '__main__':
+    unittest.main()