This folder contains a testing framework for validating the debugging behaviour of the generated js. It currently has 2 suits: One for (legacy) DDC and one for DDC with kernel (DDK).
Running the tests likely requires the compilation of the correct targets. DDK currently also requires ddc_sdk.dill
inside ./out/ReleaseX64/gen/utils/dartdevc/ddc_sdk.dill
. This should be remedied at some point.
All tests are plain Dart files and goes in “testfiles”. They are automatically picked up by the testing framework.
The tests files should contain comments describing where to set breakpoints, and the expected breaking positions. This is done with comments as in /*key*/
where key
can be on of the following:
i
th stop (1-indexed).i
th stop (1-indexed). Only check the line number.i
and j
(1-indexed). From can also be the special value 0 meaning from the beginning. For example nbb:0:1
means not before first expected stop.i
th stop (1-indexed).Note that in an ideal world bc:{i}
would be unnecessary: Stopping at a line and stepping should generally be enough. Because of the current behaviour of d8 though, for instance
baz(foo(), bar())
will stop at baz
, go into foo
, stop at bar
, go into bar
and stop at baz
. From a Dart perspective we would instead expect it to stop at foo
, go into foo
, stop at bar
,
go into bar
and stop a baz
. Having bc:{i} allows us to force this behaviour as d8 can actually stop at foo
too.
All of these annotations are removed before compiling to js and the expected output thus refers to the unannotated code.
When the test confirms that the debugger broke at the expected locations it allows for additional breakpoints before, between and after the expected breakpoints.
One can filter which tests are run by running (from the sourcemap folder):
dart sourcemaps_ddc_suite.dart -- sourcemaps_ddc//printing_class_fields
One can additionally get debug output for failing tests (i.e. tests with different outcome than expected), e.g.:
dart sourcemaps_ddc_suite.dart -Ddebug=true -- sourcemaps_ddc//printing_class_fields
Some of the logic comes from https://github.com/ChromeDevTools/devtools-frontend/, for instance see https://github.com/ChromeDevTools/devtools-frontend/blob/fa18d70a995f06cb73365b2e5b8ae974cf60bd3a/ front_end/sources/JavaScriptSourceFrame.js#L1520-L1523 for how a line breakpoint is resolved: Basically the line asked to break on in user code (e.g. in dart code) is asked for first and last javascript positions; these are then used to get possible breakpoints in that part. If there are none it tries the next line (etc for a number of lines). Once it finds something (in javascript positions) it converts that to user code position (e.g. in dart code), normalizes it by converting to javascript position and back to user code position again, then converts to javascript position and sets the breakpoint. This is to some extend mimicked here when setting a line break (though not a “column break”).