Apex テストのテストデータを作成する

@IsTest
public with sharing class TestDataFactory {
  public static List<Account> createAccountsWithOpps(Integer numAccts, Integer numOppsPerAcct) {
    List<Account> accts = new List<Account>();
    for(Integer i=0;i<numAccts;i++) {
      Account a = new Account(Name='TestAccount' + i);
      accts.add(a);
    }
    insert as user accts;
    List<Opportunity> opps = new List<Opportunity>();
    for(Integer j=0;j<numAccts;j++) {
      Account acct = accts[j];
      // For each account just inserted, add opportunities
      for(Integer k=0;k<numOppsPerAcct;k++) {
        opps.add(new Opportunity(Name=acct.Name + ' Opportunity ' + k,
          StageName='Prospecting',
          CloseDate=System.today().addMonths(1),
          AccountId=acct.Id));
      }
    }
    // Insert all opportunities for all accounts.
    insert as user opps;
    return accts;
  }
}

@IsTest
private with sharing class TestAccountDeletion {
  @IsTest
  static void TestDeleteAccountWithOneOpportunity() {
    // Test data setup
    // Create one account with one opportunity by calling a utility method
    Account[] accts = TestDataFactory.createAccountsWithOpps(1,1);
    // Perform test
    Test.startTest();
      Database.DeleteResult result = Database.delete(accts[0], false, AccessLevel.USER_MODE);
    Test.stopTest();
    // Verify that the deletion should have been stopped by the trigger,
    // so check that we got back an error.
    Assert.isFalse(result.isSuccess());
    Assert.isTrue(result.getErrors().size() > 0);
    Assert.areEqual('Cannot delete account with related opportunities.',
      result.getErrors()[0].getMessage());
  }
}

@IsTest
private with sharing class TestAccountDeletion {
  @IsTest
  static void TestDeleteAccountWithOneOpportunity() {
    // Test data setup
    // Create one account with one opportunity by calling a utility method
    Account[] accts = TestDataFactory.createAccountsWithOpps(1,1);
    // Perform test
    Test.startTest();
      Database.DeleteResult result = Database.delete(accts[0], false, AccessLevel.USER_MODE);
    Test.stopTest();
    // Verify that the deletion should have been stopped by the trigger,
    // so check that we got back an error.
    Assert.isFalse(result.isSuccess());
    Assert.isTrue(result.getErrors().size() > 0);
    Assert.areEqual('Cannot delete account with related opportunities.',
      result.getErrors()[0].getMessage());
  }
  @IsTest
  static void TestDeleteAccountWithNoOpportunities() {
    // Test data setup
    // Create one account with no opportunities by calling a utility method
    Account[] accts = TestDataFactory.createAccountsWithOpps(1,0);
    // Perform test
    Test.startTest();
      Database.DeleteResult result = Database.delete(accts[0], false, AccessLevel.USER_MODE);
    Test.stopTest();
    // Verify that the deletion was successful
    Assert.isTrue(result.isSuccess());
  }
  @IsTest
  static void TestDeleteBulkAccountsWithOneOpportunity() {
    // Test data setup
    // Create accounts with one opportunity each by calling a utility method
    Account[] accts = TestDataFactory.createAccountsWithOpps(200,1);
    // Perform test
    Test.startTest();
      Database.DeleteResult[] results = Database.delete(accts, false, AccessLevel.USER_MODE);
    Test.stopTest();
    // Verify for each record.
    // In this case the deletion should have been stopped by the trigger,
    // so check that we got back an error.
    for(Database.DeleteResult dr : results) {
      Assert.isFalse(dr.isSuccess());
      Assert.isTrue(dr.getErrors().size() > 0);
      Assert.areEqual('Cannot delete account with related opportunities.',
        dr.getErrors()[0].getMessage());
    }
  }
  @IsTest
  static void TestDeleteBulkAccountsWithNoOpportunities() {
    // Test data setup
    // Create accounts with no opportunities by calling a utility method
    Account[] accts = TestDataFactory.createAccountsWithOpps(200,0);
    // Perform test
    Test.startTest();
      Database.DeleteResult[] results = Database.delete(accts, false, AccessLevel.USER_MODE);
    Test.stopTest();
    // For each record, verify that the deletion was successful
    for(Database.DeleteResult dr : results) {
      Assert.isTrue(dr.isSuccess());
    }
  }
}