refactor: rewrite the merge-revert section

It is an advanced and difficult revert to accomplish and should probably
be done through a reset instead, which means that we're modifying
history which is dangerous and so should be handled by someone who
understands these dangers.

01-essentials/06-revert/verify.ps1

@@ -1,16 +1,16 @@
 #!/usr/bin/env pwsh
 <#
 .SYNOPSIS
-    Verifies the Module 05 challenge solutions.
+    Verifies the Module 06 challenge solutions.
 
 .DESCRIPTION
     Checks that all three revert scenarios have been completed correctly:
     - regular-revert: Single commit reverted
-    - merge-revert: Merge commit reverted with -m flag
+    - middle-revert: Commit in middle of history reverted
     - multi-revert: Multiple commits reverted
 #>
 
-Write-Host "`n=== Verifying Module 05: Git Revert Solutions ===" -ForegroundColor Cyan
+Write-Host "`n=== Verifying Module 06: Git Revert Solutions ===" -ForegroundColor Cyan
 
 $allChecksPassed = $true
 $originalDir = Get-Location
@@ -87,53 +87,50 @@ if ($LASTEXITCODE -ne 0) {
 }
 
 # ============================================================================
-# SCENARIO 2: Merge Revert Verification
+# SCENARIO 2: Middle Revert Verification
 # ============================================================================
-Write-Host "`n=== Scenario 2: Merge Revert ===" -ForegroundColor Cyan
+Write-Host "`n=== Scenario 2: Middle Revert ===" -ForegroundColor Cyan
 
-git switch merge-revert 2>&1 | Out-Null
+git switch middle-revert 2>&1 | Out-Null
 
 if ($LASTEXITCODE -ne 0) {
-    Write-Host "[FAIL] merge-revert branch not found" -ForegroundColor Red
+    Write-Host "[FAIL] middle-revert branch not found" -ForegroundColor Red
     $allChecksPassed = $false
 } else {
-    # Check that a revert commit for the merge exists
-    $revertMerge = git log --oneline --grep="Revert.*Merge" 2>$null
-    if ($revertMerge) {
-        Write-Host "[PASS] Merge revert commit found" -ForegroundColor Green
+    # Check that a revert commit exists
+    $revertCommit = git log --oneline --grep="Revert" 2>$null
+    if ($revertCommit) {
+        Write-Host "[PASS] Revert commit found" -ForegroundColor Green
     } else {
-        Write-Host "[FAIL] No merge revert commit found" -ForegroundColor Red
-        Write-Host "[HINT] Use: git revert -m 1 <merge-commit-hash>" -ForegroundColor Yellow
+        Write-Host "[FAIL] No revert commit found" -ForegroundColor Red
+        Write-Host "[HINT] Use: git revert <commit-hash>" -ForegroundColor Yellow
         $allChecksPassed = $false
     }
 
-    # Check that the original merge commit still exists (revert doesn't erase it)
-    $mergeCommit = git log --merges --oneline --grep="Merge feature-auth" 2>$null
-    if ($mergeCommit) {
-        Write-Host "[PASS] Original merge commit still in history (not erased)" -ForegroundColor Green
+    # Check that formatter.py is removed (reverted)
+    if (-not (Test-Path "formatter.py")) {
+        Write-Host "[PASS] Broken formatter.py successfully reverted (file removed)" -ForegroundColor Green
     } else {
-        Write-Host "[INFO] Original merge commit not found (this is OK if you used a different approach)" -ForegroundColor Yellow
+        Write-Host "[FAIL] formatter.py still exists (should be reverted)" -ForegroundColor Red
+        Write-Host "[HINT] The bad commit should be reverted, removing formatter.py" -ForegroundColor Yellow
+        $allChecksPassed = $false
     }
 
-    # Check that auth.py no longer exists or its effects are reverted
-    if (-not (Test-Path "auth.py")) {
-        Write-Host "[PASS] auth.py removed (merge reverted successfully)" -ForegroundColor Green
+    # Check that validation.py still exists (good commit before bad one)
+    if (Test-Path "validation.py") {
+        Write-Host "[PASS] validation.py preserved (good commit before bad one)" -ForegroundColor Green
     } else {
-        Write-Host "[INFO] auth.py still exists (check if merge was fully reverted)" -ForegroundColor Yellow
+        Write-Host "[FAIL] validation.py missing (should still exist)" -ForegroundColor Red
+        $allChecksPassed = $false
     }
 
-    # Check that calculator.py exists
-    if (Test-Path "calculator.py") {
-        $calcContent = Get-Content "calculator.py" -Raw
-
-        # After reverting the merge, calculator shouldn't import auth
-        if ($calcContent -notmatch "from auth import") {
-            Write-Host "[PASS] Auth integration reverted from calculator.py" -ForegroundColor Green
-        } else {
-            Write-Host "[FAIL] calculator.py still imports auth (merge not fully reverted)" -ForegroundColor Red
-            Write-Host "[HINT] Reverting the merge should remove the auth integration" -ForegroundColor Yellow
-            $allChecksPassed = $false
-        }
+    # Check that config.py still exists (good commit after bad one)
+    if (Test-Path "config.py") {
+        Write-Host "[PASS] config.py preserved (good commit after bad one)" -ForegroundColor Green
+    } else {
+        Write-Host "[FAIL] config.py missing (should still exist)" -ForegroundColor Red
+        Write-Host "[HINT] Only revert the bad commit, not the good ones after it" -ForegroundColor Yellow
+        $allChecksPassed = $false
     }
 }
 
@@ -211,11 +208,11 @@ if ($allChecksPassed) {
     Write-Host "=========================================" -ForegroundColor Green
     Write-Host "`nYou've mastered git revert!" -ForegroundColor Cyan
     Write-Host "You now understand:" -ForegroundColor Cyan
-    Write-Host "  ✓ Reverting regular commits safely" -ForegroundColor White
-    Write-Host "  ✓ Reverting merge commits with -m flag" -ForegroundColor White
+    Write-Host "  ✓ Reverting commits safely without erasing history" -ForegroundColor White
+    Write-Host "  ✓ Reverting old commits in the middle of history" -ForegroundColor White
     Write-Host "  ✓ Reverting multiple commits at once" -ForegroundColor White
-    Write-Host "  ✓ Preserving history while undoing changes" -ForegroundColor White
-    Write-Host "`nReady for Module 06: Git Reset!" -ForegroundColor Green
+    Write-Host "  ✓ Preserving commits before and after the reverted one" -ForegroundColor White
+    Write-Host "`nReady for Module 07: Git Reset!" -ForegroundColor Green
     Write-Host ""
     exit 0
 } else {