When no test level is specified in the deployment options, the default test execution behavior depends on the contents of your deployment package. When deploying to production, all tests, except those that originate from managed packages, are executed if your deployment package contains Apex classes or triggers. If your package doesn’t contain Apex components, no tests are run by default.
In API version 33.0 and earlier, tests were run for components that required tests, such as custom objects, and not only for Apex components. For example, if your package contains a custom object, all tests are run in API version 33.0 and earlier. In contrast, starting with API version 34.0, no tests are run for this package. The API version corresponds to the version of your API client or the version of the tool you’re using (Ant Migration Tool).
You can run tests for a deployment of non-Apex components. You can override the default test execution behavior by setting the test level in your deployment options. Test levels are enforced regardless of the types of components present in your deployment package. We recommend that you run all local tests in your development environment, such as sandbox, before deploying to production. Running tests in your development environment reduces the number of tests needed to run in a production deployment.
Default Test Execution in Production for API Version 33.0 and Earlier
For deployment to a production organization, all local tests in your organization are run by default. Tests that originate from installed managed packages aren’t run by default. If any test fails, the entire deployment is rolled back.
If the deployment includes components for the following metadata types, all local tests are run.
ApexClass
ApexComponent
ApexPage
ApexTrigger
ArticleType
BaseSharingRule
CriteriaBasedSharingRule
CustomField
CustomObject
DataCategoryGroup
Flow
InstalledPackage
NamedFilter
OwnerSharingRule
PermissionSet
Profile
Queue
RecordType
RemoteSiteSetting
Role
SharingReason
Territory
Validation Rules
Workflow
For example, no tests are run for the following deployments:
1 CustomApplication component
100 Report components and 40 Dashboard components
But all local tests are run for any of the following example deployments, because they include at least one component from the list above:
1 CustomField component
1 ApexComponent component and 1 ApexClass component
5 CustomField components and 1 ApexPage component
100 Report components, 40 Dashboard components, and 1 CustomField component