Stack traces for failures reported by Truth are cleaned so that they are more readable and useful to developers.
The Effects of Cleaning
Categories of stack frames that commonly clutter stack traces are identified by
package name prefixes. These categories are defined by
StackTraceCleaner.StackFrameType.
If two or more adjacent stack frames belong to the same category, the entire series of those frames will be collapsed into a single frame summarizing what the frames were doing (ex: “Reflective call”).
Some frames are not collapsed and are instead stripped from the stack entirely. Frames for Truth are removed from the top of the stack so that the first displayed frame is likely the failing assertion. Testing framework (JUnit, etc.) and reflective call frames are removed from the bottom of the stack, since these will not be helpful in determining why a test failed.
Disable Stack Trace Cleaning
Stack trace cleaning is enabled by default. To disable the cleaning and have
Truth report the original stack traces, set the system property
com.google.common.truth.disable_stack_trace_cleaning to true.
To disable the feature for the current process:
System.setProperty("com.google.common.truth.disable_stack_trace_cleaning", "true");