--- schema_version: "1" id: 07aa559e1af49b62a9cfd6b3a1c66aa660361313f969b2daf8f794ebf8bf9e81 title: Assert Class collection: legacydeveloper version: current locale: en-us portal_url: https://docs.salesforce.com/legacydeveloper/current/en-us/apexref/apex_class_System_Assert.md canonical_url: https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm source_site: developer.salesforce.com content_type: documentation content_hash: 14dea123cafeaff02a9f4052ac78a40684536d045130a6315eab45c508b35b07 description: Contains methods to assert various conditions with test methods, such as whether two values are the same, a condition is true, or a variable is null. Asserts that the first two arguments are the same. Asserts that the two arguments are the same. Asserts that the first two arguments aren’t the same. Asserts that the two arguments aren’t the same. Immediately return a fatal error that causes code execution to halt.Immediately return a fatal error that causes code execution to halt.Asserts that the specified condition is false. Asserts that the specified condition is false. Asserts that the instance is of the specified type. Asserts that the instance is of the specified type. Asserts that the instance isn’t of the specified type. Asserts that the instance isn’t of the specified type. Asserts that the value isn’t null. Asserts that the value isn’t null. Asserts that the value is null. Asserts that the value is null. Asserts that the specified condition is true. Asserts that the specified condition is true. --- # Assert Class Contains methods to assert various conditions with test methods, such as whether two values are the same, a condition is true, or a variable is null. ## Namespace [System](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_namespace_System.htm "The System namespace provides classes and methods for core Apex functionality.") ## Assert Methods The following are methods for Assert. - **[areEqual(expected, actual, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_areEqual)** Asserts that the first two arguments are the same. - **[areEqual(expected, actual)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_areEqual_2)** Asserts that the two arguments are the same. - **[areNotEqual(notExpected, actual, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_areNotEqual)** Asserts that the first two arguments aren’t the same. - **[areNotEqual(notExpected, actual)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_areNotEqual_2)** Asserts that the two arguments aren’t the same. - **[fail(msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_fail)** Immediately return a fatal error that causes code execution to halt. - **[fail()](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_fail_2)** Immediately return a fatal error that causes code execution to halt. - **[isFalse(condition, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isFalse)** Asserts that the specified condition is false. - **[isFalse(condition)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isFalse_2)** Asserts that the specified condition is false. - **[isInstanceOfType(instance, expectedType, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isInstanceOfType)** Asserts that the instance is of the specified type. - **[isInstanceOfType(instance, expectedType)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isInstanceOfType_2)** Asserts that the instance is of the specified type. - **[isNotInstanceOfType(instance, notExpectedType, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isNotInstanceOfType)** Asserts that the instance isn’t of the specified type. - **[isNotInstanceOfType(instance, notExpectedType)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isNotInstanceOfType_2)** Asserts that the instance isn’t of the specified type. - **[isNotNull(value, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isNotNull)** Asserts that the value isn’t null. - **[isNotNull(value)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isNotNull_2)** Asserts that the value isn’t null. - **[isNull(value, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isNull)** Asserts that the value is null. - **[isNull(value)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isNull_2)** Asserts that the value is null. - **[isTrue(condition, msg)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isTrue)** Asserts that the specified condition is true. - **[isTrue(condition)](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_class_System_Assert.htm#apex_System_Assert_isTrue_2)** Asserts that the specified condition is true. ### areEqual(expected, actual, msg) Asserts that the first two arguments are the same. #### Signature public static void areEqual(Object expected, Object actual, String msg) #### Parameters - **expected**: Type: Object Expected value. - **actual**: Type: Object Actual value. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the first two arguments aren't the same, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String sub = 'abcde'.substring(2); Assert.areEqual('cde', sub, 'Expected characters after first two'); // Succeeds ### areEqual(expected, actual) Asserts that the two arguments are the same. #### Signature public static void areEqual(Object expected, Object actual) #### Parameters - **expected**: Type: Object Expected value. - **actual**: Type: Object Actual value. #### Return Value Type: void #### Usage If the two arguments aren't the same, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String sub = 'abcde'.substring(2); Assert.areEqual('cde', sub); // Succeeds ### areNotEqual(notExpected, actual, msg) Asserts that the first two arguments aren’t the same. #### Signature public static void areNotEqual(Object notExpected, Object actual, String msg) #### Parameters - **notExpected**: Type: Object Value that’s not expected. - **actual**: Type: Object Actual value. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the first two arguments are the same, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String sub = 'abcde'.substring(2); Assert.areNotEqual('xyz', sub, 'Characters not expected after first two'); // Succeeds ### areNotEqual(notExpected, actual) Asserts that the two arguments aren’t the same. #### Signature public static void areNotEqual(Object notExpected, Object actual) #### Parameters - **notExpected**: Type: Object Value that’s not expected. - **actual**: Type: Object Actual value. #### Return Value Type: void #### Usage If the two arguments are the same, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String sub = 'abcde'.substring(2); Assert.areNotEqual('xyz', sub); // Succeeds ### fail(msg) Immediately return a fatal error that causes code execution to halt. #### Signature public static void fail(String msg) #### Parameters - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage Commonly used in a try/catch block test case where an exception is expected to be thrown. You can’t, however, catch the assertion failure in the try/catch block even though it’s logged as an exception. #### Example // test case where exception is expected try { SomeClass.methodUnderTest(); Assert.fail('DmlException Expected'); } catch (DmlException ex) { // Add assertions here about the expected exception } ### fail() Immediately return a fatal error that causes code execution to halt. #### Signature public static void fail() #### Return Value Type: void #### Usage Commonly used in a try/catch block test case where an exception is expected to be thrown. You can’t, however, catch the assertion failure in the try/catch block even though it’s logged as an exception. #### Example // test case where exception is expected try { SomeClass.methodUnderTest(); Assert.fail(); } catch (DmlException ex) { // Add assertions here about the expected exception } ### isFalse(condition, msg) Asserts that the specified condition is false. #### Signature public static void isFalse(Boolean condition, String msg) #### Parameters - **condition**: Type: [Boolean](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_boolean.htm#apex_methods_system_boolean "Contains methods for the Boolean primitive data type.") Condition you’re checking to determine if it’s false. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the condition is true, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Boolean containsCode = 'Salesforce'.contains('code'); Assert.isFalse(containsCode, 'No code'); // Assertion succeeds ### isFalse(condition) Asserts that the specified condition is false. #### Signature public static void isFalse(Boolean condition) #### Parameters - **condition**: Type: [Boolean](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_boolean.htm#apex_methods_system_boolean "Contains methods for the Boolean primitive data type.") Condition you’re checking to determine if it’s false. #### Return Value Type: void #### Usage If the condition is true, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Boolean containsCode = 'Salesforce'.contains('code'); Assert.isFalse(containsCode); // Assertion succeeds ### isInstanceOfType(instance, expectedType, msg) Asserts that the instance is of the specified type. #### Signature public static void isInstanceOfType(Object instance, System.Type expectedType, String msg) #### Parameters - **instance**: Type: Object Instance whose type you're checking. - **expectedType**: Type: [System.Type](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_type.htm#apex_methods_system_type "Contains methods for getting the Apex type that corresponds to an Apex class and for instantiating new types.") Expected type. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the instance isn't of the specified type, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Account o = new Account(); Assert.isInstanceOfType(o, Account.class); // Succeeds ### isInstanceOfType(instance, expectedType) Asserts that the instance is of the specified type. #### Signature public static void isInstanceOfType(Object instance, System.Type expectedType) #### Parameters - **instance**: Type: Object Instance whose type you're checking. - **expectedType**: Type: [System.Type](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_type.htm#apex_methods_system_type "Contains methods for getting the Apex type that corresponds to an Apex class and for instantiating new types.") Expected type. #### Return Value Type: void #### Usage If the instance isn't of the specified type, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Account o = new Account(); Assert.isInstanceOfType(o, Account.class); // Succeeds Account o = new Account(); Assert.isInstanceOfType(o, Account.class, 'Expected type.'); // Succeeds ### isNotInstanceOfType(instance, notExpectedType, msg) Asserts that the instance isn’t of the specified type. #### Signature public static void isNotInstanceOfType(Object instance, System.Type notExpectedType, String msg) #### Parameters - **instance**: Type: Object Instance whose type you're checking. - **notExpectedType**: Type: [System.Type](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_type.htm#apex_methods_system_type "Contains methods for getting the Apex type that corresponds to an Apex class and for instantiating new types.") Type that's not expected. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the instance is of the specified type, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Contact con = new Contact(); Assert.isNotInstanceOfType(con, Account.class, 'Not expected type'); // Succeeds ### isNotInstanceOfType(instance, notExpectedType) Asserts that the instance isn’t of the specified type. #### Signature public static void isNotInstanceOfType(Object instance, System.Type notExpectedType) #### Parameters - **instance**: Type: Object Instance whose type you're checking. - **notExpectedType**: Type: [System.Type](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_type.htm#apex_methods_system_type "Contains methods for getting the Apex type that corresponds to an Apex class and for instantiating new types.") Type that's not expected. #### Return Value Type: void #### Usage If the instance is of the specified type, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Contact con = new Contact(); Assert.isNotInstanceOfType(con, Account.class); // Succeeds ### isNotNull(value, msg) Asserts that the value isn’t null. #### Signature public static void isNotNull(Object value, String msg) #### Parameters - **value**: Type: Object Value you’re checking to determine if it’s not null. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the value is null, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String myString = 'value'; Assert.isNotNull(myString, 'myString should not be null'); // Succeeds ### isNotNull(value) Asserts that the value isn’t null. #### Signature public static void isNotNull(Object value) #### Parameters - **value**: Type: Object Value you’re checking to determine if it’s not null. #### Return Value Type: void #### Usage If the value is null, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String myString = 'value'; Assert.isNotNull(myString); // Succeeds ### isNull(value, msg) Asserts that the value is null. #### Signature public static void isNull(Object value, String msg) #### Parameters - **value**: Type: Object Value you’re checking to determine if it’s null. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the value isn't null, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String myString = null; Assert.isNull(myString, 'String should be null'); // Succeeds ### isNull(value) Asserts that the value is null. #### Signature public static void isNull(Object value) #### Parameters - **value**: Type: Object Value you’re checking to determine if it’s null. #### Return Value Type: void #### Usage If the value isn't null, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example String myString = null; Assert.isNull(myString); // Succeeds ### isTrue(condition, msg) Asserts that the specified condition is true. #### Signature public static void isTrue(Boolean condition, String msg) #### Parameters - **condition**: Type: [Boolean](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_boolean.htm#apex_methods_system_boolean "Contains methods for the Boolean primitive data type.") Condition you’re checking to determine if it’s true. - **msg**: Type: [String](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_string.htm#apex_methods_system_string "Contains methods for the String primitive data type.") (Optional) Custom message returned as part of the error message. #### Return Value Type: void #### Usage If the specified condition is false, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Boolean containsForce = 'Salesforce'.contains('force'); Assert.isTrue(containsForce, 'Contains force'); // Assertion succeeds ### isTrue(condition) Asserts that the specified condition is true. #### Signature public static void isTrue(Boolean condition) #### Parameters - **condition**: Type: [Boolean](https://developer.salesforce.com/docs/atlas.en-us.apexref.meta/apexref/apex_methods_system_boolean.htm#apex_methods_system_boolean "Contains methods for the Boolean primitive data type.") Condition you’re checking to determine if it’s true. #### Return Value Type: void #### Usage If the specified condition is false, a fatal error is returned that causes code execution to halt. You can’t catch an assertion failure using a try/catch block even though it’s logged as an exception. #### Example Boolean containsForce = 'Salesforce'.contains('force'); Assert.isTrue(containsForce); // Assertion succeeds