Knowledge Base > Troubleshooting > Output codes

Output codes

Meaning of Diffblue Cover output codes.

The possible codes are described below:

E codes

Code Meaning Example Suggestion
E001 Failed to insert a test into the created test Java file Please enable read and write permissions on file SomeJavaFile.java and its parent folder.
E002 Failed to overwrite the created test Java file Please enable read and write permissions on file SomeJavaFile.java and its parent folder.
E003 Failed to read the existing test Java file Please enable read permissions on file SomeJavaFile.java and its parent folder.
E010 JUnit dependencies version mismatch Diffblue Cover may produce non-passing tests because the $BUILDSYSTEM configuration contains mismatching versions of junit-platform-commons ($VERSION) and junit-jupiter-api ($VERSION). Please see the prerequisite information.
E011 Test validation command failed Diffblue Cover may produce non-passing tests because running $VALIDATION_CMD failed:$BUILD_LOG

For further information please see information on validation. You may also find information on output code V003 useful.
E013 Failed to create test Java file Please enable read and write permissions on folder $DIR
E014 Required dependency not found Diffblue Cover could not start because a dependency could not be found. Make sure that all required dependencies are installed in paths where Diffblue Cover can find them.
E015 Failed to download junit-platform-launcher artifact Diffblue Cover may produce non-passing tests because it failed to download $ARTIFACT due to $EXCEPTION. Make sure that $ARTIFACT can be downloaded from $URL.
E016 Failed to connect to analysis service Make sure that local firewall settings allow connecting to a service at $HOST:$PORT.
E045 Validation command failed for unknown reasons Cover tried and failed to validate the tests it generated, using `$command` as the validation command. The output from running this command is available in the log file, see the last lines of $logfile. While Cover could not figure out the reason for this and cannot fix it automatically, this issue is usually due to an incorrect validation command, or due to the failure of existing, user-provided tests.
E048 Current JVM does not support JDK which compiled the project Diffblue Cover is running on one JVM version, but your project was built with another JDK version. Diffblue Cover needs to be executed with the same or a more recent Java version than the version with which the project was compiled. The following classes were compiled with an old JDK version: $CLASSES. Either recompile the project with Java version that Diffblue Cover is running in, or run Diffblue Cover with JVM version that you used to compile the project. Please see the prerequisite information.
E049 inotify limit too low Try restarting the IDE and/or your machine. Check your inotify limit with sudo sysctl fs.inotify.max_user_watches, try setting it to a higher value with sudo sysctl fs.inotify.max_user_watches=<new-value>. You can make this change permanent by following the instructions on JetBrains website.
E054 No class files found Diffblue Cover could not find any .class files for your project. This usually indicates that your project has not yet been compiled.

For Maven, run mvn install -DskipTests from the root of the project.

For Gradle, run gradle :compileJava from the root of the project.

Depending on your project setup, additional configuration may be required.
E055 Failed to compile a simple example test Diffblue Cover tried to compile a simple example test to help it figure out the right project configuration, but the test failed to compile when running the validation command.

F codes

Code Meaning Example Suggestion
F001 Internal Error Failed to close a class loader. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.
F002 Internal Error Failed to execute test. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.
F003 Internal Error Failed to execute test. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.
F004 Internal Error Failed to execute test. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.
F009 Internal Error Failed to execute test. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.
F018 Failed to extract inputs from recorded execution trace Failed to execute test. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.

R codes

Code Meaning Example Suggestion
R002 Missing observers Diffblue Cover was unable to create an assertion. Add getters for the following fields or make them package-private: $FULLY_QUALIFIED_FIELDS $FIELDS
R003 No accessible observers Diffblue Cover was unable to create an assertion. Make the following methods package-private: $FULLY_QUALIFIED_OBSERVERS $GETTERS
R004 No meaningful assertions found Diffblue Cover was unable to create an assertion. Make sure that fields modified by $MUT have package-private, protected or public getters.
R005 Unable to load class Please check that $CLASS is available on your test runtime classpath.
R006 Static initializer failed The static initializer of $CLASS_IDENTIFIER threw an exception $EXCEPTION while trying to load it. Make sure the static initializer of $CLASS can be executed without throwing exceptions.
R007 No accessible constructor or factory method Diffblue Cover was unable to construct an instance of $CLASS. Make one of the following constructors or factory methods package-private: $CONSTRUCTORS_FACTORIES
R008 Failed to instantiate class under test Diffblue Cover was unable to construct an instance of $CLASS. Add a package-visible constructor or a factory method for testing which (ideally) takes no arguments, and does not throw, return null or return a subtype.
R010 Timeout Creating the arrange/act section of your test took more than $PER_METHOD_TIMEOUT seconds. This often happens because Diffblue Cover ran code in your project which requests user input (System.in), blocks on a lock, or runs into an infinite or very long loop.
R011 Sandboxing policy violation Diffblue Cover ran code in your project that tried $SANDBOX_VIOLATION_REASON. Diffblue Cover’s default sandboxing policy disallows this in order to prevent your system from overwriting your files or opening network connections.
R013 No inputs found that don’t throw a trivial exception Diffblue Cover tried to run the following arrange/act section, but it threw a trivial exception. Add constructors or factory methods that make it easier to construct objects of the following classes in order to prevent $METHOD from throwing $EXCEPTION_NAME: $CLASSES.
R015 Method under test may be nondeterministic Diffblue Cover tried to run the following test twice, but it first passed the assertions and then failed.
R019 Method under test not called in recorded execution trace Record your program again and provide program inputs that trigger at least one call of the method $METHOD.
R020 Temporary files not cleaned up The method under test created temporary files without deleting them: $FILES. Please ensure that temporary files are deleted after use.
R021 Missing Spring components Diffblue Cover detected Spring on the classpath, but is missing critical classes to load the Spring context: $CLASSES.
R022 Failed to load trace file Continuing with the loaded fragment of the trace. Record your program again. If the problem persists please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.
R024 Out of resources Diffblue Cover failed to create tests for method $METHOD because its execution seems to exceed available resources (memory, threads, file handles, etc).
R025 Skipped due to previous failure Diffblue Cover failed to create tests for $FAILED_METHOD and thus skipped all methods in class $CLASS.
R026 Failed to create Spring context Attempted to initialize test context using a class $CLASS but threw exception $EXCEPTION
R027 Failed to load Spring Boot application context Diffblue Cover may not be able to produce tests for methods invoked by Spring.

T codes

Code Meaning Suggestion
T001 Trivial getter.  Information only.
T002 Trivial setter.  Information only.
T003 Private method.  The method is declared private or in a private inner class. It cannot be called from another class in the same package. Diffblue Cover will attempt to test it indirectly through other callable methods. If you want to test this method directly make it package-private.
T004 In anonymous inner class The method is declared in an anonymous inner class. It cannot be called directly. Diffblue Cover will attempt to test it indirectly through other callable methods. If you want to test this method directly factor out the anonymous class into a package-private class.
T005 Trivial constructor Information only.
T006 Main method It is difficult to assert on side effects of main methods in a unit test. Refactor the main method. E.g. factor out its body into a separate, accessible method that returns the results that should be asserted on.
T007 Framework configuration callbacks Certain framework callbacks (e.g. Spring’s @InitBinder) should not be directly tested because they have side effects. Diffblue Cover will attempt to test it indirectly through other callable methods.
T008 Private and never called The method cannot be called from another class in the same package. It is not called by any other method and therefore cannot be tested. If this method is called by reflection then annotate it with @SuppressWarnings(“unused”). If the method is indeed dead code then remove it from your code base.
T010 Abstract or interface method Information only.
T011 The method is annotated @SuppressWarnings ("unused") The method is declared private and annotated with @SuppressWarnings(\“unused\”). This indicates that the method is probably called by reflection. The method will not be tested directly. If you want to test this method directly then make it package-private and remove the annotation.
T020 Other trivial method Information only.
T021 Empty method body Information only.

V codes

Code Meaning Suggestion
V003 Test discarded during validation Please see the separate article: Working with code V003.

W codes

Code Meaning Suggestion
W001 Test did not compile Diffblue Cover removed the following test because it did not compile. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.
W002 Test compiled but did not pass Diffblue Cover removed the following test because it did not pass when run. Please contact Diffblue through the appropriate support channel (https://www.diffblue.com/support) providing details about this error.