git-workshop/02_advanced/04-bisect/setup.ps1

#!/usr/bin/env pwsh

<#
.SYNOPSIS
    Sets up the bisect challenge environment.

.DESCRIPTION
    Creates a Git repository with multiple commits where a bug is
    introduced in one of them. Students use bisect to find it.
#>

# Remove existing challenge directory if present
if (Test-Path "challenge") {
    Write-Host "Removing existing challenge directory..." -ForegroundColor Yellow
    Remove-Item -Path "challenge" -Recurse -Force
}

# Create challenge directory
Write-Host "Creating challenge environment..." -ForegroundColor Cyan
New-Item -ItemType Directory -Path "challenge" | Out-Null
Set-Location "challenge"

# Initialize git repository
git init | Out-Null
git config user.name "Workshop User" | Out-Null
git config user.email "user@workshop.local" | Out-Null

# Commit 1: Initial calculator
$calc1 = @"
class Calculator:
    def add(self, a, b):
        return a + b
"@
Set-Content -Path "calculator.py" -Value $calc1
git add calculator.py
git commit -m "Initial calculator with add function" | Out-Null

# Commit 2: Add subtract
$calc2 = @"
class Calculator:
    def add(self, a, b):
        return a + b

    def subtract(self, a, b):
        return a - b
"@
Set-Content -Path "calculator.py" -Value $calc2
git add calculator.py
git commit -m "Add subtract function" | Out-Null

# Commit 3: Add multiply
$calc3 = @"
class Calculator:
    def add(self, a, b):
        return a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b
"@
Set-Content -Path "calculator.py" -Value $calc3
git add calculator.py
git commit -m "Add multiply function" | Out-Null

# Commit 4: Add divide
$calc4 = @"
class Calculator:
    def add(self, a, b):
        return a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b

    def divide(self, a, b):
        if b == 0:
            raise ValueError('Division by zero')
        return a / b
"@
Set-Content -Path "calculator.py" -Value $calc4
git add calculator.py
git commit -m "Add divide function" | Out-Null

# Commit 5: Add modulo
$calc5 = @"
class Calculator:
    def add(self, a, b):
        return a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b

    def divide(self, a, b):
        if b == 0:
            raise ValueError('Division by zero')
        return a / b

    def modulo(self, a, b):
        return a % b
"@
Set-Content -Path "calculator.py" -Value $calc5
git add calculator.py
git commit -m "Add modulo function" | Out-Null

# Commit 6: BUG - Introduce error in add function
$calc6 = @"
class Calculator:
    def add(self, a, b):
        return a - b  # BUG: Should be a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b

    def divide(self, a, b):
        if b == 0:
            raise ValueError('Division by zero')
        return a / b

    def modulo(self, a, b):
        return a % b
"@
Set-Content -Path "calculator.py" -Value $calc6
git add calculator.py
git commit -m "Refactor add function for clarity" | Out-Null

# Commit 7: Add power function (bug still exists)
$calc7 = @"
class Calculator:
    def add(self, a, b):
        return a - b  # BUG: Should be a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b

    def divide(self, a, b):
        if b == 0:
            raise ValueError('Division by zero')
        return a / b

    def modulo(self, a, b):
        return a % b

    def power(self, a, b):
        return a ** b
"@
Set-Content -Path "calculator.py" -Value $calc7
git add calculator.py
git commit -m "Add power function" | Out-Null

# Commit 8: Add square root
$calc8 = @"
import math

class Calculator:
    def add(self, a, b):
        return a - b  # BUG: Should be a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b

    def divide(self, a, b):
        if b == 0:
            raise ValueError('Division by zero')
        return a / b

    def modulo(self, a, b):
        return a % b

    def power(self, a, b):
        return a ** b

    def sqrt(self, a):
        return math.sqrt(a)
"@
Set-Content -Path "calculator.py" -Value $calc8
git add calculator.py
git commit -m "Add square root function" | Out-Null

# Commit 9: Add absolute value
$calc9 = @"
import math

class Calculator:
    def add(self, a, b):
        return a - b  # BUG: Should be a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b

    def divide(self, a, b):
        if b == 0:
            raise ValueError('Division by zero')
        return a / b

    def modulo(self, a, b):
        return a % b

    def power(self, a, b):
        return a ** b

    def sqrt(self, a):
        return math.sqrt(a)

    def abs(self, a):
        return abs(a)
"@
Set-Content -Path "calculator.py" -Value $calc9
git add calculator.py
git commit -m "Add absolute value function" | Out-Null

# Commit 10: Add max function
$calc10 = @"
import math

class Calculator:
    def add(self, a, b):
        return a - b  # BUG: Should be a + b

    def subtract(self, a, b):
        return a - b

    def multiply(self, a, b):
        return a * b

    def divide(self, a, b):
        if b == 0:
            raise ValueError('Division by zero')
        return a / b

    def modulo(self, a, b):
        return a % b

    def power(self, a, b):
        return a ** b

    def sqrt(self, a):
        return math.sqrt(a)

    def abs(self, a):
        return abs(a)

    def max(self, a, b):
        return a if a > b else b
"@
Set-Content -Path "calculator.py" -Value $calc10
git add calculator.py
git commit -m "Add max function" | Out-Null

# Create a test file
$test = @"
import sys
from calculator import Calculator

calc = Calculator()

# Test addition (this will fail due to bug)
result = calc.add(5, 3)
if result != 8:
    print(f'FAIL: add(5, 3) returned {result}, expected 8')
    sys.exit(1)

print('PASS: All tests passed')
sys.exit(0)
"@
Set-Content -Path "test.py" -Value $test

# Return to module directory
Set-Location ..

Write-Host "`n========================================" -ForegroundColor Green
Write-Host "Challenge environment created!" -ForegroundColor Green
Write-Host "========================================" -ForegroundColor Green
Write-Host "`nSituation:" -ForegroundColor Cyan
Write-Host "The calculator has a bug - addition doesn't work correctly!" -ForegroundColor Red
Write-Host "calc.add(5, 3) returns 2 instead of 8" -ForegroundColor Red
Write-Host "`nThe bug was introduced somewhere in the last 10 commits." -ForegroundColor Yellow
Write-Host "Manually checking each commit would be tedious." -ForegroundColor Yellow
Write-Host "Use git bisect to find it efficiently!" -ForegroundColor Green
Write-Host "`nYour task:" -ForegroundColor Yellow
Write-Host "1. Navigate to the challenge directory: cd challenge" -ForegroundColor White
Write-Host "2. Test the bug: python test.py (it will fail)" -ForegroundColor White
Write-Host "3. Start bisect: git bisect start" -ForegroundColor White
Write-Host "4. Mark current as bad: git bisect bad" -ForegroundColor White
Write-Host "5. Mark old commit as good: git bisect good HEAD~10" -ForegroundColor White
Write-Host "6. Git will checkout a commit - test it: python test.py" -ForegroundColor White
Write-Host "7. Mark result: git bisect good (if test passes) or git bisect bad (if it fails)" -ForegroundColor White
Write-Host "8. Repeat until Git finds the first bad commit" -ForegroundColor White
Write-Host "9. Note the commit hash" -ForegroundColor White
Write-Host "10. End bisect: git bisect reset" -ForegroundColor White
Write-Host "11. Create bug-commit.txt with the bad commit hash" -ForegroundColor White
Write-Host "`nHint: The bug is in commit 6 ('Refactor add function for clarity')" -ForegroundColor Cyan
Write-Host "Run '../verify.ps1' from the challenge directory to check your solution.`n" -ForegroundColor Cyan