binman: Allow preserving test directories

Sometimes when debugging tests it is useful to keep the input and output
directories so they can be examined later. Add an option for this and
update the binman tests to support it. This affects both the test class
and the tearDown() function called after each test.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/binman.py b/tools/binman/binman.py
index 7c1dcfb6..9878eb8 100755
--- a/tools/binman/binman.py
+++ b/tools/binman/binman.py
@@ -46,15 +46,20 @@
 import control
 import test_util
 
-def RunTests(debug, verbosity, processes, args):
+def RunTests(debug, verbosity, processes, test_preserve_dirs, args):
     """Run the functional tests and any embedded doctests
 
     Args:
         debug: True to enable debugging, which shows a full stack trace on error
         verbosity: Verbosity level to use
+        test_preserve_dirs: True to preserve the input directory used by tests
+            so that it can be examined afterwards (only useful for debugging
+            tests). If a single test is selected (in args[0]) it also preserves
+            the output directory for this test. Both directories are displayed
+            on the command line.
+        processes: Number of processes to use to run tests (None=same as #CPUs)
         args: List of positional args provided to binman. This can hold a test
             name to execute (as in 'binman -t testSections', for example)
-        processes: Number of processes to use to run tests (None=same as #CPUs)
     """
     import elf_test
     import entry_test
@@ -82,6 +87,11 @@
     loader = unittest.TestLoader()
     for module in (entry_test.TestEntry, ftest.TestFunctional, fdt_test.TestFdt,
                    elf_test.TestElf, image_test.TestImage):
+        # Test the test module about our arguments, if it is interested
+        if hasattr(module, 'setup_test_args'):
+            setup_test_args = getattr(module, 'setup_test_args')
+            setup_test_args(preserve_indir=test_preserve_dirs,
+                preserve_outdirs=test_preserve_dirs and test_name is not None)
         if test_name:
             try:
                 suite.addTests(loader.loadTestsFromName(test_name, module))
@@ -157,7 +167,7 @@
 
     if options.test:
         ret_code = RunTests(options.debug, options.verbosity, options.processes,
-                            args[1:])
+                            options.test_preserve_dirs, args[1:])
 
     elif options.test_coverage:
         RunTestCoverage()