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Knowledge Base > Troubleshooting > Output codes

Output codes

Meaning of Diffblue Cover output codes.

The possible codes are described below:

E - Environment codes

Code Meaning Suggestion
E001 Failed to insert a test Diffblue Cover failed to write a test in the test Java file. Please enable read and write permissions on the file.
E002 Failed to overwrite the created test Java file Failed to overwrite the created test Java file. Please enable read and write permissions on the file and its parent folder.
E003 Failed to read existing test Java file Failed to read the existing test Java file. Please enable read permissions on this file and its parent folder.
E004 No methods found to test Diffblue Cover was unable to find any methods that can be tested in your selection. Ensure that your selection includes some Java code that contains methods that are not private.
If using the --patch-only option, ensure that the patch file was created correctly and that its encoding is UTF-8.
E005 Parent module without classes You must run dcover on the individual submodules. Run dcover with the option --working-directory path/to/submodule or change into the submodule directory and run dcover from there.
E006 JUnit Jupiter Launcher not found Diffblue Cover cannot verify the generated tests because the JUnit Jupiter Launcher was not found. We have detected that you have JUnit Jupiter on your classpath but were not able run a dummy test. Because of this, Diffblue Cover has disabled test verification. Please ensure that your build system is configured to run JUnit Jupiter tests (for Maven projects, ensure the Surefire plugin is configured to run JUnit Jupiter tests; for Gradle projects, ensure that useJUnitPlatform() is in the test configuration. You can also use --testing-framework=junit-4 to force Diffblue Cover to write JUnit4 tests.
E007 Missing classes detected Diffblue Cover could not execute a Dummy Test in your project. A number of classes were detected as missing. Because of this Diffblue Cover will not be able to verify tests. Please resolve these missing classes to enable test verification.
E008 Missing a critical JUnit Jupiter class Diffblue Cover was not able to run a dummy test in your environment because the ClassNamePatternFilterUtils class was missing. This can occur when you have a mismatch in versions of the junit-platform-launcher and junit-platform-commons. Please ensure that these versions are consistent. If you don't have a junit-platform-launcher specified, please add an appropriate version to your project. Because of this Diffblue Cover will not be able to verify tests.
E009 Unexpected launcher detection output While trying to detect the path to the JUnit Jupiter Launcher, we detected multiple lines of output where we expected only a single line. Because of this Diffblue Cover will not be able to verify tests.
E010 Invalid patch depth The --patch-depth parameter controls the number of hops from the classes in the patch dcover will consider when generating tests. A value of 0 will create tests for just the classes in the patch, while a value of 1 will create tests for any class that uses those in the patch (as well as the ones mentioned in the patch), and so on.

Care must be taken as there are occasions where the impact of the changes in the patch may not be detected and you may end up with test failures because the impact of the patch hasn't propagated to the necessary extent.
E011 Failed to run a simple example test Problems in the local build system have been detected that will prevent Diffblue Cover from verifying and validating the created tests.
E012 Error when using build system An error occurred when using the build system. Check the user log file in .diffblue/log which contains the entire build system log to find the build system error message.
E013 Compatible launcher not found Diffblue Cover was not able to find a JUnit Jupiter Launcher compatible with your configured JUnit Jupiter Engine. Please adjust your build configuration to use compatible JUnit Jupiter Engine versions. Because of this, Diffblue Cover will not be able to verify tests.
E014 No build system found Neither Gradle nor Maven build systems were detected. Use the --classpath option or CLASSPATH environment variable to specify a classpath manually.
E015 Specified build system not available The specified build system is not available. Make sure a build configuration file for the specified build system is available in the project, or enable auto-detection of the build system by dropping the --gradle or --maven options you might be using.
E016 Failed to connect to analysis service Make sure that local firewall settings allow connecting to a service at HOST:PORT.
E017 Trace loading error Failed to load execution trace. Please review the cause message to diagnose the underlying issue.
E018 Working directory does not exist The specified working directory does not exist. Make sure you have specified an existing directory when using the --working-directory option.
E019 Failed to create .diffblue directory Diffblue Cover failed to create its .diffblue directory in the working directory. Make sure Diffblue Cover has the correct permissions to create a directory.
E020 Failed to start up analysis service Please see Working with code E020.
E021 Multiple 'settings.gradle' files There are multiple settings.gradle files in your project, which may cause your project configuration to be invalid. Consolidate the content of your settings.gradle files into a single file at the root of your project, and remove all other settings.gradle files.
E022 JUnit Jupiter Launcher location Diffblue Cover was not able to discover the path to the JUnit Jupiter Launcher. Because of this Diffblue Cover will not be able to verify tests.
E023 A file could not be deleted The given file could not be deleted. If deletion is necessary, please do this manually.
E024 Multiple files could not be deleted The given files could not be deleted. If deletion is necessary, please do this manually.
E025 Unable to download the launcher Diffblue Cover uses the JUnit Jupiter Launcher to run verify tests. While attempting to download the launcher we encountered an error. Because of this, Diffblue Cover has disabled test verification.
E026 Custom validation command unsuccessful Diffblue Cover was not able to execute the custom validation command successfully and has disabled test validation.
E027 JUnit Jupiter Engine not found Diffblue Cover was not able to find a JUnit Jupiter Engine configured in your project's dependencies. Diffblue Cover uses this to determine the version of the JUnit Jupiter Launcher to use when verifying tests. Please ensure that your project is configured to run JUnit Jupiter tests. Because of this, Diffblue Cover will not be able to verify tests.
E028 Cannot determine dependencies Diffblue Cover was not able to determine the dependencies of your project. Check the build system output in the user log file for further information. Because of this Diffblue Cover is not able to verify tests.
E029 Invalid trace directory Failed to select a trace from the trace directory. Please review the cause message to diagnose the underlying issue.
E030 Test creation cancelled Test creation for this method was cancelled as requested.
E031 Unsupported Java language version We recommend you change your module settings to JDK 1.8, JDK 11, or JDK 17.
E032 Failing tests detected while validating Diffblue Cover tried to validate the tests it created but failed due to failing tests. Diffblue Cover cannot fix this problem automatically. The output from running the validation command is available towards the end of the log file. Please see our documentation for further guidance.
E033 JUnit Jupiter versions mismatch Diffblue Cover discovered a mismatch in JUnit Jupiter Api and Engine versions.
Please ensure that your JUnit Jupiter Api and Engine versions match.
Because of this, Diffblue Cover will not be able to verify tests.
E034 Running existing tests took too long Diffblue Cover tried to run a command to run all the existing tests, but it took too long. The output from running the command is available towards the end of the log file.
E035 Running existing tests failed Diffblue Cover tried to run a command to run all the existing tests, but it failed. The output from running this command is available towards the end of the log file. While Diffblue Cover could not figure out the reason for this and cannot fix it automatically, this issue is usually due to an incorrect command, or due to the failure of existing, user-provided tests.
E036 Existing test failures Diffblue Cover tried to run all the existing the tests but failed due to failing tests. Diffblue Cover cannot fix this problem automatically. The output from running the validation command is available towards the end of the log file.
E041 Failed to apply refactoring Failed to apply refactoring. Check the build system output in the user log file for further information.
E042 Failed to write refactoring config file Failed to write refactoring configuration file. Please enable write permissions on this file and its parent folder.
E043 Failed to install into Maven repository Failed to install a file into the local Maven repository. Make sure the displayed command can be executed successfully.
E044 Incompatible user options The two given options are incompatible. Remove one of them.
E045 Validation command failed for unknown reasons Diffblue Cover tried and failed to validate the tests it created. The output from running this command is available towards the end of the log file. While Diffblue 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. Please see our documentation for further guidance.
E046 Failed to load Maven settings Failed to load Maven settings.xml files from the user's home directory or maven installation directory. Make sure that Maven commands can be executed successfully, using your settings.
E047 Unsupported Java version Please use Java 8 Update 351+, Java 11.0.17+ or Java 17.0.5+.
E048 Invalid JaCoCo report file Diffblue Cover was unable to read the given JaCoCo report file.
E049 inotify limit too low The current inotify watch limit is too low. Try restarting the IDE and/or your machine. Check your inotify limit and consider resetting to a higher value.
E050 Unsupported tool version Unfortunately the version of the specified tool you are using is unsupported. Please consider upgrading.
E051 Current JVM does not support JDK which compiled the project Diffblue Cover needs to be executed with the same or a more recent Java version than the version with which the project was compiled.
E052 Missing dependency Required dependencies were not found. Please add these dependencies.
E053 Unsupported dependency A dependency was found at an unsupported version. Please upgrade it to the given version.
E054 No class files found Diffblue Cover could not find any .class files for your project. This usually means that your project has not yet been compiled.
E055 Failed to compile a simple example test For Diffblue Cover to run successfully, we require an example test to pass. Please see our documentation.
E056 JDK not found Diffblue Cover requires a JDK (Java Development Kit) to run. A JRE (Java Runtime Environment) is not sufficient. Diffblue Cover expects the JDK in RT_JAR_PATH or JMODS_PATH. Make sure a JDK is installed in these locations.
E057 Service startup certificate problem There was a problem with the SSL certificates used to set up the connection. Check whether you have the full set of CA certificates for Java installed.
E058 Service startup I/O problem There was an I/O problem while trying to set up a network connection to the service. Please check whether you have a firewall configuration that disallows TCP servers on localhost.
E059 Service startup message timeout If your machine is heavily loaded or very slow, try reducing load before running Cover.
E060 Service startup SSL problem Please contact Diffblue Support, providing details about this error.
E061 Service startup timeout If your machine is heavily loaded or very slow, try reducing load before running Cover.
E062 Service JVM exited unexpectedly Please contact Diffblue Support, providing details about this error.
E063 Diffblue Cover component missing A Diffblue Cover component is missing. Please check your installation is complete.
E064 Service startup I/O failure Starting up the service failed because of an I/O problem while trying to execute the JVM for the service process. Please check whether your installation is complete, whether all files are readable and whether the JVM in JAVA_HOME is executable.
E065 Service startup interrupted Please contact Diffblue Support, providing details about this error.
E066 Dependency incompatible with JDK Some dependencies are incompatible with the current JDK (version). Please add the following dependencies to your project (list).
E067 JVM not a 64-bit implementation Diffblue Cover requires a 64-bit JVM to run. A 32-bit JVM is not sufficient. Make sure a 64-bit JDK 8, 11 or 17 is installed and JAVA_HOME is set to its installation location.
E068 Failed to load custom input rules Diffblue Cover tried to load custom input rules but was unable to read the content of the file correctly. Please review the content of the custom input file and ensure that it is correct. Information about the input rules format can be found in our documentation.
E069 Environment checks failed Please check your environment. More information on the runtime environment can be found in our documentation.
E070 Compilation failed Diffblue Cover cannot write tests because your project failed to compile. Please ensure that your project compiles successfully before trying to write tests again.
E071 Surefire version mismatch Diffblue Cover detected an old version of the Maven Surefire plugin in use in your project. Because of this Diffblue Cover will not be able to verify tests. Additionally, this version is not sufficient to produce coverage reports. Please upgrade the the most recent version. If you are using JUnit Jupiter 5, you need a minimum of 3.0.0-M7. If you are using JUnit 4, you need a minimum of 2.19.
E072 Surefire missing Diffblue Cover detected an old version of the Maven Surefire plugin in use in your project. Because of this Diffblue Cover will not be able to verify tests. Please upgrade the the most recent version. If you are using JUnit Jupiter 5, you need a minimum of 3.0.0-M4. If you are using JUnit 4, you need a minimum of 2.3.
E073 Static mocking is not configured The --mock-static option was specified, but your project has not been configured to use the Mockito inline mock maker. Mockito recommends placing the mockito-inline artifact where you are currently using mockito-core.
E074 Mockito test dependency not found The --mock-static option was specified, but Mockito is not present in your project. Please add Mockito to your project as a test dependency.
E075 Static mocking is not supported The --mock-static option was specified, but your version of Mockito is not sufficient to support static mocking. Please upgrade your version of Mockito to at least version 3.4.0.
E077 Invalid trace file found Unable to load the trace. Please record your application again with the Replay agent of your current installation of Diffblue Cover.
E078 Writing report failed Diffblue Cover tried and failed to write a report. Check to see if you have the correct permissions to write to the file, or use a different path for the report.
E079 Failed to create test output directory Diffblue Cover failed to create the test output directory (e.g. src/test/java). Make sure Diffblue Cover has the correct permissions to create a directory.
E080 Invalid patch file Diffblue Cover was unable to read the given patch file.
E081 Failed to write file Failed to write the coverage report. Please check permissions.
E082 Could not find JaCoCo report The JaCoCo report could not be found. To troubleshoot, try running the logged command and check that the coverage report is created at the expected location.
E083 Error while producing JaCoCo report The JaCoCo command failed for an unknown reason. Please check the user log file.
E084 JaCoCo command failed The JaCoCo command returned a non-zero exit code. Please check the user log file. This happens when there are no tests to run. If this is unexpected, make sure JaCoCo is setup in the project.
E085 Attempt to compile a test as Groovy Please ensure the build configuration compiles Diffblue tests as java.
E086 Specified test framework not available The test framework specified is not available on the classpath. Please add it as a dependency.
E087 Multiple testing frameworks, select one There are multiple testing frameworks available in your build configuration, and it is not clear which of them should be used by Cover. Please use the --testing-framework option to select a testing framework, e.g. --testing-framework=junit-4 or --testing-framework=junit-5.
E088 No supported test framework on classpath A supported version of JUnit is not available on the classpath. Please add at least one supported JUnit version to the classpath. For a Spring Boot project, this should be done by adding the spring-boot-test dependency.
E089 Can't parse specified test framework The test framework argument provided is not a valid, supported JUnit version. Please refer to our documentation for the list of supported versions.
E091 Failed to load execution policy rules Diffblue Cover tried to load custom execution policy rules but was unable to read the content of the file correctly. Please review the content of the custom execution policy rules file and ensure that it is correct.
E092 Missing embedded database engine No embedded Java database engines were detected. This will prevent Diffblue Cover from writing tests for repository classes. Spring supports HSQL, H2, and Derby. Please add one of these as a dependency to your project. Alternatively, if you are not interested in testing repository classes, they can be excluded using the --exclude option.
E093 jacoco-maven-plugin is too old The version of the jacoco-maven-plugin is too old to support the prepare-agent and report goals needed to generate the coverage reports. Please adjust your pom.xml to use version 0.8.7.
To view coverage data in Cover Reports we use the prepare-agent and report goals of the jacoco-maven-plugin to record the coverage as the tests are executed. These goals are not available in your currently configured version of the plugin.
E094 jacoco-maven-plugin doesn't produce XML The jacoco-maven-plugin is not configured to produce the XML output format. Please add XML to the list of <formats> in the configuration, e.g. 
...
  <plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.8.7</version>
    <configuration>
      <formats>HTML,XML</formats>
    </configuration>
    <executions>
      <execution>
        <id>jacoco-initialize</id>
        <goals>
          <goal>prepare-agent</goal>
        </goals>
      </execution>
      <execution>
        <id>jacoco-site</id>
        <phase>test</phase>
        <goals>
          <goal>report</goal>
        </goals>
      </execution>
    </executions>
  </plugin>
...

The XML coverage report is used by Cover Reports to show the coverage produced by Diffblue Cover alongside the developer written tests.
E095 Project properties set to skip JaCoCo Tests were generated, but we couldn't measure the coverage. This is because a jacoco.skip property is being set to true in the pom.xml of the project under test. Please remove this property, or set it to false to measure the coverage.
E096 Required file missing for upload One of the report files was not available when we tried to upload them to Diffblue Cover Reports. This can be caused either by the reports not being created, or being moved before the upload started. See working with Cover Reports for more information.
E097 Cover Reports server connection problem We couldn't connect to the Diffblue Cover Reports server. This could be due to a wide number of reasons, for example:
  • Cover Reports isn't running, or the server is down
  • The Cover Reports hostname is not able to be resolved
  • There's a firewall blocking the connection between the machine and Cover Reports
  • The connection between the client and the server is too slow
If you were running as part of the create command you can use upload to avoid recreating all the tests. If you are still experiencing problems, please contact Diffblue Support.
E098 Diffblue Cover Reports server error The Diffblue Cover Reports server was not able to process the upload request. Please contact Diffblue Support.
E099 Cover Reports upload was successful The upload was successful.
E100 Cover Reports upload was successful The upload was successful.
E101 Cover Reports upload status unknown The upload was unknown because we didn't get a response from the server to indicate whether the upload was successful. Check your reports and see if the upload succeeded, if not, please try again. If you believe this is a problem, please contact Diffblue Support and provide this message along with the logs.
E102 Cover Reports upload was successful The upload was successful but the server sent a response we were not expecting. Please check your logs and contact Diffblue Support if you believe there is a problem.
E103 Gradle project root not found Diffblue Cover was unable to find the root of your gradle project. Check the user log file in .diffblue/log which contains the build system log to find the build system error messages.
E104 Mockito failed to initialize Mockito failed to initialize for some reason. Likely resulting from a dependency mismatch. Review the quoted message and address the concerns in order to create tests using mocks.
E105 No active Spring profile specified This project uses Spring profiles but no profile was supplied through the --active-profiles option. Use the --active-profiles option to explicitly specify the profiles to use. If a Spring profile named "test" was available, Diffblue Cover would select it automatically.
E107 Incompatible Spring dependency The dependency is not compatible with spring-core. Diffblue Cover may not be able to create Spring tests correctly. Consider upgrading your dependency.
E108 Invalid method specification Invalid method prefixes were specified by the user.
E109 Max heap size too low Diffblue Cover running without sufficient memory allocated. Please use the JVM_ARGS environment variable to increase the memory allocation.
E110 Timeout running a simple example test Problems in the local build system have been detected that will prevent Diffblue Cover from verifying and validating the created tests.
E111 Credentials were not supplied Authentication stopped while uploading coverage reports because password or username were not supplied. Please check your input arguments (--report-username and --report-password), or environment variables (DIFFBLUE_REPORT_USERNAME and DIFFBLUE_REPORT_PASSWORD).
E112 Incorrect credentials Authentication stopped while uploading coverage reports because username or password are incorrect. Please check your input arguments (--report-username and --report-password), or environment variables (DIFFBLUE_REPORT_USERNAME and DIFFBLUE_REPORT_PASSWORD).
E113 Credentials were supplied but not needed Authentication has not been enabled on your Cover Reports instance, so you do not need to provide a username or password. Please remove `DIFFBLUE_REPORT_USERNAME` and `DIFFBLUE_REPORT_PASSWORD` environment variables and `--report-username` and `--report-password` input arguments. Alternatively, you can enable authentication on your Cover Reports instance. See https://docs.diffblue.com/knowledge-base/diffblue-cover-reports/authentication/ for details on how to do this.
E114 Unable to access project The project asset was disposed. This is likely because your project configuration changed during an operation. Please rebuild the project and try again.
E115 Incorrect JaCoCo coverage reported JaCoCo reported incorrect coverage for a simple example class. Please check your JaCoCo configuration and ensure JaCoCo runs as expected on your system. This is commonly seen with an out of date Surefire version, so ensure you are using a supported version.
E116 JaCoCo XML file missing JaCoCo failed to create coverage for a simple example class. Please check your JaCoCo configuration and ensure JaCoCo runs as expected on your system.
E117 JaCoCo coverage task failed The JaCoCo coverage task failed. Please check your JaCoCo configuration and ensure JaCoCo runs as expected on your system.
E118 JUnit Vintage Engine not found Diffblue Cover cannot verify the generated tests because the JUnit Vintage Engine was not found. We have detected that you have dependencies on both JUnit 4 and JUnit Jupiter 5, however without the JUnit Vintage Engine, we will be unable to run any JUnit 4 tests. Please ensure that your build system is configured to run JUnit 4 tests if you also have a dependency on JUnit Jupiter 5.
E130 Invalid characters in template The template must only use valid Java identifier characters (a-z,A-Z,0-9,$,_) and must not start with a digit. Remove the illegal characters.
E131 Unterminated variable in template The template contains an unterminated variable (${ without closing }). Fix this variable.
E132 Invalid variable in template The template contains an unrecognized variable. Remove this variable. In class templates only ${CLASS_NAME} is allowed. In method templates only ${METHOD_NAME} and ${INNER_CLASS_NAME} are allowed.
E133 No variable in template The template does not contain any variable to include the class or method name.
E134 Only variable in template The specified class name template consists only of the variable ${CLASS_NAME}. This would clash with the class under test. For example, try to add a suffix: ${CLASS_NAME}Test
E135 Class name too long The specified class name template has too much static text (more than 128 characters). This would probably lead to class file names too long to store on disk.
E136 N/a Information only

L - Licensing codes

Code Meaning Suggestion
L003 Too many methods marked for analysis Writing tests for these methods could use up your remaining budget of tests. Consider writing tests for a single class or method at a time so that the number of methods to write tests for is less than your budget limit.
L004 License activated too many times Your license has been activated too many times. Please contact either your license administrator or Diffblue Support.
L005 The license has expired Your license has expired - please contact your license administrator or purchase a new one on our pricing page.
L006 Exceeded license limitations You have exceeded the limit for your license. Please contact either your license administrator or Diffblue Support, or see our pricing page for information on increasing the limit.
L007 The license is not active Your license is not active. Please contact either your license administrator or Diffblue Support.
L008 The license is not enabled Your license is not enabled. Please contact either your license administrator or Diffblue Support.
L009 License key not found Please check that the license key you entered is correct. If you still have problems, please contact either your license administrator or Diffblue Support.
L010 License server unreachable Diffblue Cover cannot access the Diffblue license verification server. Each time Diffblue Cover writes tests it authenticates your license against the Diffblue remote license verification server. Check that you have an active internet connection and that any firewall rules allow outbound connections to https://api.licensespring.com and https://licensing.diffblue.com/
Diffblue Cover Enterprise Edition supports offline activation and offline use. The current status of the Diffblue license server can be found at https://status.diffblue.com
L011 Failed to encrypt/decrypt license file The installed Java version does not provide the required cryptographic algorithms. Please install a newer version of the JDK.
L012 Unable to verify license Either your licence file has expired, it has been corrupted, or you are activating an offline license response with the wrong key. Please contact your license administrator or Diffblue Support.
L013 Features not available with this license Some features are not available with your version of Diffblue Cover. Please contact your licence administrator or see here for information on our editions and on upgrading.
L014 Activation required You have not activated your licence yet. For the CLI, run dcover activate with your license key to activate your license. For the plugin, click Diffblue and Activate License in the menu bar to activate your license. If you do not have a license key then please contact your license administrator or purchase one from Diffblue.
L015 License is read-only Ensure your license file can be written to.
L016 Hardware configuration has changed Computer hardware configuration has changed or the license does not belong to this computer. For the CLI, run dcover activate with your license key to activate your license. For the plugin, click Diffblue and Activate License in the menu bar to activate your license.
L017 Failed to activate Community Edition Diffblue Cover was unable to obtain a Community Edition license. Please try again later or contact Diffblue Support.
L018 Licensing server SSL certificate error This indicates that something between your machine and the licensing server is intercepting your connection. This is usually caused by some sort of firewall configuration. For help, please contact your license administrator or Diffblue Support.
L019 Offline mode not supported by license You have attempted to run Diffblue Cover in offline mode, however that feature is not supported by your current licence.
Delete the offline license directory to return to online mode.
Only Diffblue Cover Enterprise Edition supports offline activation and offline use.
L020 Offline license has not been activated An offline license is present but has not yet been activated. Run dcover activate --offline to activate your offline license.
Only Diffblue Cover Enterprise Edition supports offline activation and offline use.
L022 Offline mode not reset You have deleted your offline license file, however you have not properly restarted your IDE.
Please close all IDE windows and ensure your IDE is fully exited before restarting.
L023 Access denied Diffblue was unable to access your license in the .diffblue folder. Please grant suitable permissions to this directory.

R - Reason codes

(reasons for tests not being created that may have a work around)

Code Meaning Suggestion
R002 Missing observers There are no fields that could be asserted on. Add getters or make the fields package-private.
R005 Unable to load class Please check that the class is available on your test runtime classpath. See our documentation for further guidance.
R006 Static initializer failed A static initializer threw an exception while trying to load a class. Make sure static initializers can be executed without throwing exceptions.
R007 Class not accessible Make sure all classnames are accessible from their targetPackage, for example by making them public.
R008 Failed to instantiate class under test Diffblue Cover was unable to construct an instance of someClass. Ensure there is a package-visible constructor or factory method that does not throw an exception for the class under test. If such a method is already present but Diffblue Cover does not find it, it can be specified using custom rules for inputs: custom-inputs
See Working with code R008 for further troubleshooting of this issue.
R011 Sandboxing policy violation Diffblue Cover's default sandboxing policy disallowed test writing in order to prevent your code from damaging your system environment. Please see Working with code R011.
R012 JNI sandbox policy violation Diffblue Cover ran code in your project that tried to load a JNI library, violating the default security policy. See Java Native Interface to resolve this issue.
R013 No inputs found that don't throw a trivial exception Diffblue Cover tried to run the arrange/act section, but the method under test threw an error. Add constructors or factory methods that make it easier to construct fully initialized objects. Please see Working with code R013.
R018 Trace file incomplete The method under test could not be found in the execution trace. The trace file was only partially loaded because an error was found while loading it. Please record your application again with the Replay agent of your current installation of Cover.
R019 Method not in trace The method under test is not called in recorded execution trace. Record your program again and provide program inputs that trigger at least one call of the method under test.
R020 Temporary files were created but not deleted Please ensure that temporary files are deleted in the method under test.
R021 Missing Spring component Diffblue Cover detected Spring on the classpath, but failed to load critical components while building the Spring context. Make sure these components can be loaded.
R023 Out of memory Diffblue Cover failed to create tests because it ran out of memory.
See: Memory Management
R026 Failed to create Spring context Failed to create Spring context. Check to see if there are any missing environment variables or system properties. For detailed and further troubleshooting please see Working with code R026.
R027 Missing beans when creating Spring context Failed to create Spring context due to missing beans. Check to see if there are any missing environment variables or system properties. Also missing beans could be defined in Spring profiles that aren't used for test generation. Otherwise, please contact Diffblue Support with details of the entire output message and the source code of the class under test.
R028 Incomplete repository information Try extending CrudRepository with concrete type parameters, or if the class should not be considered a repository then annotate the class with the @NoRepositoryBean annotation.
R031 Method may be time-sensitive Please see Working with code R031 for details.
R032 User requested skeleton tests only Information only.
R033 Missing Spring properties Some classes in the Spring context have @Value annotation that Diffblue Cover can't resolve. Usually variables for such annotations are provided in *.properties files. Please check src/main/resources and src/test/resources. The default names for the files are application.properties and application-test.properties. If you use named Spring profiles please use application-<profile name>.properties files.
R034 Diffblue Cover can't complete test Diffblue Cover needs to run a number of construction steps to create a test. If the number of steps allowed when setting --fuzzing-iterations=N parameter is not enough then Diffblue Cover stops with no tests written. In this case try to allow more iterations by setting N to a higher value.
R074 Unable to create static mock Mockito was unable to create a static mock for a class. Please review the underlying cause in the output message or log.
R081 Exception in arrange section Diffblue Cover was unable to construct an instance of the class under test because a step in the arrange section threw an exception.
R082 Can't create a parameter for constructor Diffblue Cover was unable to construct an instance.
Diffblue Cover failed to create a parameter for the constructor or factory method call.
R083 Can't find a suitable constructor Diffblue Cover was unable to construct an instance.
No suitable constructor or factory method found. Please check that the class under test has a non-private constructor or factory method.
R084 Enum has no constants defined Diffblue Cover was unable to test an instance of an enum as no constants are defined.

T - Testability codes

Code Meaning Suggestion
T000 Should be tested directly Information only.
T001 Trivial getter Information only.
T002 Trivial setter Diffblue Cover will not attempt to create a test for this method. It may be tested indirectly.
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 Diffblue Cover will not attempt to create a test for this constructor. It may be tested indirectly. Default constructors of static utility classes are considered trivial.
T006 Main method 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 callback Certain framework callbacks should not be directly tested because of possible side effects. Diffblue Cover will attempt to test 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 the method is dead code then remove it from your code base.
T009 No implementation for abstract class The method is a non-abstract instance method in an abstract class or a default method in an interface. Diffblue Cover would test such methods by using an implementation of that abstract class or interface. However, no such implementation has been found. Please provide an implementation for the abstract class or interface.
T010 Abstract or interface method Information only.
T012 Synthetic method Indicates that the method is synthetic. Currently, this includes methods:
  • that are marked as synthetic by the compiler
  • that are not directly callable
  • that are generated by frameworks, e.g. Hibernate
  • that exist on the JDK class but do not appear in the source code
Diffblue Cover considers these methods as not directly callable.
T020 Other trivial method Information only.
T021 Empty method body Diffblue Cover will not attempt to create a test for this method.
T022 Cannot test mocked method The method under test is not unit-testable because it must be mocked.
T023 Testability unknown Indicates that the testability could not be determined for the method. Diffblue Cover considers these methods as not testable.
T033 Method excluded from test creation Diffblue Cover did not create tests for this method as the user chose to exclude them. If you wish to have tests created for this class, please check that it is not within the --exclude option.

V - Validation codes

Code Meaning Suggestion
V003 Tests discarded during validation Please see Working with code V003 for further details.