{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Hypothesis: _Property_ -basiertes Testen\n",
    "\n",
    "In diesem Notebook verwenden wir _Property_ -basierte Tests, um Probleme in unserem Code zu finden. [Hypothesis](https://hypothesis.readthedocs.io/en/latest/) ist eine Bibliothek, die Haskells [Quickcheck](https://hackage.haskell.org/package/QuickCheck) ähnelt. Später lernen wir sie zusammen mit anderen Testbibliotheken noch genauer kennen: [Hypothesis](https://jupyter-tutorial.readthedocs.io/de/latest/notebook/testing/hypothesis.html). Hypothesis kann auch Mock-Objekte und Tests für Numpy-Datentypen bereitstellen."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 1. Importe"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "execution": {
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    }
   },
   "outputs": [],
   "source": [
    "import re\n",
    "\n",
    "from hypothesis import given\n",
    "from hypothesis.strategies import emails, integers, tuples"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 2. Bereich finden"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "execution": {
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     "shell.execute_reply.started": "2026-05-22T13:50:23.967664Z"
    }
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   "outputs": [],
   "source": [
    "def calculate_range(tuple_obj):\n",
    "    return max(tuple_obj) - min(tuple_obj)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 3. Test mit `strategies` und `given`\n",
    "\n",
    "Mit [hypothesis.strategies](https://hypothesis.readthedocs.io/en/latest/data.html) könnt ihr unterschiedliche Testdaten erstellen. Hierfür beitet Hypothesis Strategien für die meisten Typen und Argumente schränken die Möglichkeiten ein um sie euren Erfordernissen anzupassen. Im Beispiel unten verwenden wir die [integers](https://hypothesis.readthedocs.io/en/latest/data.html#hypothesis.strategies.integers)-Strategie, die mit dem [Python-Decorator](https://docs.python.org/3/glossary.html#term-decorator) `@given` auf die Funktion angewendet wird. Genauer  nimmt er unsere Testfunktion und wandelt sie in eine parametrisierte um sie über weite Bereiche passender Daten auszuführen:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
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   "outputs": [],
   "source": [
    "@given(tuples(integers(), integers(), integers()))\n",
    "def test_calculate_range(tup):\n",
    "    result = calculate_range(tup)\n",
    "    assert isinstance(result, int)\n",
    "    assert result > 0"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
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   "outputs": [
    {
     "ename": "AssertionError",
     "evalue": "",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAssertionError\u001b[0m                            Traceback (most recent call last)",
      "Cell \u001b[0;32mIn[4], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mtest_calculate_range\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
      "Cell \u001b[0;32mIn[3], line 2\u001b[0m, in \u001b[0;36mtest_calculate_range\u001b[0;34m()\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[38;5;129m@given\u001b[39m(tuples(integers(), integers(), integers()))\n\u001b[0;32m----> 2\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mtest_calculate_range\u001b[39m(tup):\n\u001b[1;32m      3\u001b[0m     result \u001b[38;5;241m=\u001b[39m calculate_range(tup)\n\u001b[1;32m      4\u001b[0m     \u001b[38;5;28;01massert\u001b[39;00m \u001b[38;5;28misinstance\u001b[39m(result, \u001b[38;5;28mint\u001b[39m)\n",
      "    \u001b[0;31m[... skipping hidden 1 frame]\u001b[0m\n",
      "Cell \u001b[0;32mIn[3], line 5\u001b[0m, in \u001b[0;36mtest_calculate_range\u001b[0;34m(tup)\u001b[0m\n\u001b[1;32m      3\u001b[0m result \u001b[38;5;241m=\u001b[39m calculate_range(tup)\n\u001b[1;32m      4\u001b[0m \u001b[38;5;28;01massert\u001b[39;00m \u001b[38;5;28misinstance\u001b[39m(result, \u001b[38;5;28mint\u001b[39m)\n\u001b[0;32m----> 5\u001b[0m \u001b[38;5;28;01massert\u001b[39;00m result \u001b[38;5;241m>\u001b[39m \u001b[38;5;241m0\u001b[39m\n",
      "\u001b[0;31mAssertionError\u001b[0m: ",
      "\u001b[0mFalsifying example: test_calculate_range(\n    tup=(0, 0, 0),\n)"
     ]
    }
   ],
   "source": [
    "test_calculate_range()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Nun korrigieren wir den Test mit `>=` und überprüfen ihn erneut:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "execution": {
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   "outputs": [],
   "source": [
    "@given(tuples(integers(), integers()))\n",
    "def test_calculate_range(tup):\n",
    "    result = calculate_range(tup)\n",
    "    assert isinstance(result, int)\n",
    "    assert result >= 0"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "execution": {
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   "source": [
    "test_calculate_range()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 3. Gegen Reguläre Ausdrücke prüfen\n",
    "\n",
    "Mit [regulären Ausrücken](https://de.wikipedia.org/wiki/Regul%C3%A4rer_Ausdruck) (engl.: _regular expressions_) lassen sich Zeichenketten auf bestimmte syntaktische Regeln überprüfen. In Python könnt ihr zum Überprüfen regulärer Ausdrücke [re.match](https://docs.python.org/3/library/re.html#re.match) verwenden.\n",
    "\n",
    "> **Hinweis:**\n",
    "> \n",
    "> Auf der Website [regex101](https://regex101.com/) könnt ihr zunächst eure regulären Ausdrücke ausprobieren.\n",
    "\n",
    "Als Beispiel versuchen wir, aus E-Mail-Adressen `username` und die `domain` zu ermitteln:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "execution": {
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   "outputs": [],
   "source": [
    "def parse_email(email):\n",
    "    result = re.match(\n",
    "        r\"(?P<username>\\w+).(?P<domain>[\\w\\.]+)\",\n",
    "        email,\n",
    "    ).groups()\n",
    "    return result"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Nun schreiben wir einen Test `test_parse_email` zum Überprüfen unserer Methode. Als Eingabewerte verwenden wir die [emails](https://hypothesis.readthedocs.io/en/latest/data.html#hypothesis.strategies.emails)-Strategie von Hypothesis. Als `result` erwarten wir z.B.:\n",
    "```\n",
    "('0', 'A.com')\n",
    "('F', 'j.EeHNqsx')\n",
    "…\n",
    "```\n",
    "Im Test nehmen wir einerseits an, dass immer zwei Einträge zurückgegeben werden und im zweiten Eintrag ein Punkt (`.`) vorkommt. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
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   "outputs": [],
   "source": [
    "@given(emails())\n",
    "def test_parse_email(email):\n",
    "    result = parse_email(email)\n",
    "    assert len(result) == 2\n",
    "    assert \".\" in result[1]"
   ]
  },
  {
   "cell_type": "code",
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   "outputs": [
    {
     "ename": "AttributeError",
     "evalue": "'NoneType' object has no attribute 'groups'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAttributeError\u001b[0m                            Traceback (most recent call last)",
      "Cell \u001b[0;32mIn[9], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mtest_parse_email\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
      "Cell \u001b[0;32mIn[8], line 2\u001b[0m, in \u001b[0;36mtest_parse_email\u001b[0;34m()\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[38;5;129m@given\u001b[39m(emails())\n\u001b[0;32m----> 2\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mtest_parse_email\u001b[39m(email):\n\u001b[1;32m      3\u001b[0m     result \u001b[38;5;241m=\u001b[39m parse_email(email)\n\u001b[1;32m      4\u001b[0m     \u001b[38;5;28;01massert\u001b[39;00m \u001b[38;5;28mlen\u001b[39m(result) \u001b[38;5;241m==\u001b[39m \u001b[38;5;241m2\u001b[39m\n",
      "    \u001b[0;31m[... skipping hidden 1 frame]\u001b[0m\n",
      "Cell \u001b[0;32mIn[8], line 3\u001b[0m, in \u001b[0;36mtest_parse_email\u001b[0;34m(email)\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[38;5;129m@given\u001b[39m(emails())\n\u001b[1;32m      2\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mtest_parse_email\u001b[39m(email):\n\u001b[0;32m----> 3\u001b[0m     result \u001b[38;5;241m=\u001b[39m \u001b[43mparse_email\u001b[49m\u001b[43m(\u001b[49m\u001b[43memail\u001b[49m\u001b[43m)\u001b[49m\n\u001b[1;32m      4\u001b[0m     \u001b[38;5;28;01massert\u001b[39;00m \u001b[38;5;28mlen\u001b[39m(result) \u001b[38;5;241m==\u001b[39m \u001b[38;5;241m2\u001b[39m\n\u001b[1;32m      5\u001b[0m     \u001b[38;5;28;01massert\u001b[39;00m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124m.\u001b[39m\u001b[38;5;124m\"\u001b[39m \u001b[38;5;129;01min\u001b[39;00m result[\u001b[38;5;241m1\u001b[39m]\n",
      "Cell \u001b[0;32mIn[7], line 5\u001b[0m, in \u001b[0;36mparse_email\u001b[0;34m(email)\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mparse_email\u001b[39m(email):\n\u001b[1;32m      2\u001b[0m     result \u001b[38;5;241m=\u001b[39m \u001b[43mre\u001b[49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43mmatch\u001b[49m\u001b[43m(\u001b[49m\n\u001b[1;32m      3\u001b[0m \u001b[43m        \u001b[49m\u001b[38;5;124;43mr\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43m(?P<username>\u001b[39;49m\u001b[38;5;124;43m\\\u001b[39;49m\u001b[38;5;124;43mw+).(?P<domain>[\u001b[39;49m\u001b[38;5;124;43m\\\u001b[39;49m\u001b[38;5;124;43mw\u001b[39;49m\u001b[38;5;124;43m\\\u001b[39;49m\u001b[38;5;124;43m.]+)\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m,\u001b[49m\n\u001b[1;32m      4\u001b[0m \u001b[43m        \u001b[49m\u001b[43memail\u001b[49m\u001b[43m,\u001b[49m\n\u001b[0;32m----> 5\u001b[0m \u001b[43m    \u001b[49m\u001b[43m)\u001b[49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43mgroups\u001b[49m()\n\u001b[1;32m      6\u001b[0m     \u001b[38;5;28;01mreturn\u001b[39;00m result\n",
      "\u001b[0;31mAttributeError\u001b[0m: 'NoneType' object has no attribute 'groups'",
      "\u001b[0mFalsifying example: test_parse_email(\n    email='/@A.ac',\n)"
     ]
    }
   ],
   "source": [
    "test_parse_email()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Mit Hypothesis wurden zwei Beispiele gefunden, die deutlich machen, dass unser regulärer Ausdruck in der `parse_email`-Methode noch nicht hinreichend ist: `0/0@A.ac` und `/@A.ac`. Nachdem wir unseren regulären Ausdruck entsprechend angepasst haben, können wir den Test erneut aufrufen:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
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   },
   "outputs": [],
   "source": [
    "def parse_email(email):\n",
    "    result = re.match(\n",
    "        r\"(?P<username>[\\.\\w\\-\\!~#$%&\\|{}\\+\\/\\^\\`\\=\\*']+).(?P<domain>[\\w\\.\\-]+)\",\n",
    "        email,\n",
    "    ).groups()\n",
    "    return result"
   ]
  },
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   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
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   "outputs": [],
   "source": [
    "test_parse_email()"
   ]
  }
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