Bug 29018: Make DELETE /patrons/:patron_id check things

When the route was implemented, the checks were overlooked. This patch
adds checks for:
- Guarantees
- Debts
- Current checkouts

Any of those will block deletion, as it should.

To test:
1. Apply the regression tests patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/api/v1/patrons.t
=> FAIL: Tests fail, the route misses checks
3. Apply this patch
4. Repeat 2
=> SUCCESS: Tests pass! The three conditions prevent deletion!
5. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

Signed-off-by: David Nind <david@davidnind.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>

Koha/REST/V1/Patrons.pm

@@ -330,10 +330,39 @@ sub delete {
 
     return try {
 
-        $patron->delete;
-        return $c->render(
-            status  => 204,
-            openapi => q{}
+        if ( $patron->checkouts->count > 0 ) {
+            return $c->render(
+                status  => 409,
+                openapi => { error => 'Pending checkouts prevent deletion' }
+            );
+        }
+
+        my $account = $patron->account;
+
+        if ( $account->outstanding_debits->total_outstanding > 0 ) {
+            return $c->render(
+                status  => 409,
+                openapi => { error => 'Pending debts prevent deletion' }
+            );
+        }
+
+        if ( $patron->guarantee_relationships->count > 0 ) {
+            return $c->render(
+                status  => 409,
+                openapi => { error => 'Patron is a guarantor and it prevents deletion' }
+            );
+        }
+
+        $patron->_result->result_source->schema->txn_do(
+            sub {
+                $patron->move_to_deleted;
+                $patron->delete;
+
+                return $c->render(
+                    status  => 204,
+                    openapi => q{}
+                );
+            }
         );
     } catch {
         if ( blessed $_ && $_->isa('Koha::Exceptions::Patron::FailedDeleteAnonymousPatron') ) {

api/v1/swagger/paths/patrons.yaml

@@ -546,6 +546,14 @@
         description: Patron not found
         schema:
           $ref: ../definitions.yaml#/error
+      "409":
+        description: Conflict
+        schema:
+          $ref: ../definitions.yaml#/error
+      "500":
+        description: Internal server error
+        schema:
+          $ref: ../definitions.yaml#/error
     x-koha-authorization:
       permissions:
         borrowers: delete_borrowers