Fix lldb-dotest when dotest_args_str is empty

[jingham]

Summary

When - after substitution - the dotest_args_str is empty, then we were still inserting the blank string into the args. Later on, a blank arg is taken to be a directory path and gets added to the CWD (which is generally in the build directory) and then none of the actual test directories match that, so we find no tests.

This patch fixes that by not adding blank arguments in lldb-dotest.

It could also be fixed by having the dotest implementation discard empty arguments, but I wasn't sure that was always correct, maybe you are somewhere in the test suite already and want to pass "" to dial up the current directory? So I went with fixing it where we were getting it wrong instead.

[aprantl]

Interesting, I would have expected array.extend([]) be a noop?

[jingham]

Or really, we split the string, resulting in an empty array, and apparently cmd.extend([]) adds an empty argument.

[jingham]

In D133075#3762869, @aprantl wrote:

Interesting, I would have expected array.extend([]) be a noop?

Me too. Too bad the Python folks don't check with us more often...

[jingham]

In D133075#3762872, @jingham wrote:

In D133075#3762869, @aprantl wrote:

Interesting, I would have expected array.extend([]) be a noop?

Me too. Too bad the Python folks don't check with us more often...

Ah, it's not that, rather:

string = ""
arr = string.split(";")
arr

['']

[jingham]

This one actually works.

[jingham]

Actually, I confused myself because I still had the other fix in place. This would still be an array with one empty element. You have to just not do the split if the string is empty and then it works sensibly.

[aprantl]

Thanks, that makes more sense!

lldb/utils/lldb-dotest/lldb-dotest.in

 lldb_build_dir = '@LLDB_TEST_BUILD_DIRECTORY_CONFIGURED@'
 lldb_build_intel_pt = "@LLDB_BUILD_INTEL_PT@"
 lldb_framework_dir = "@LLDB_FRAMEWORK_DIR_CONFIGURED@"
 lldb_libs_dir = "@LLDB_LIBS_DIR_CONFIGURED@"
 llvm_tools_dir = "@LLVM_TOOLS_DIR_CONFIGURED@"
 
 if __name__ == '__main__':
     wrapper_args = sys.argv[1:]
+    dotest_args = []
+    # split on an empty string will produce [''] and if you
+    # add that to the command, it will be treated as a directory...
+    if len(dotest_args_str) > 0:
         dotest_args = dotest_args_str.split(';')
     # Build dotest.py command.
     cmd = [sys.executable, dotest_path]
     cmd.extend(['--arch', arch])
     cmd.extend(dotest_args)
     cmd.extend(['--build-dir', lldb_build_dir])
     cmd.extend(['--executable', executable])
     cmd.extend(['--compiler', compiler])
     cmd.extend(['--dsymutil', dsymutil])