Add a library suitable for libfuzzer with a small unit test runner shell

tools/testrunner/objects/testcase.py

Index: tools/testrunner/objects/testcase.py
diff --git a/tools/testrunner/objects/testcase.py b/tools/testrunner/objects/testcase.py
index fa2265c0703f1fecd028fde43b988d3cc54ebf01..b91f8b4b562de54b1095414af9099281ed05b432 100644
--- a/tools/testrunner/objects/testcase.py
+++ b/tools/testrunner/objects/testcase.py
@@ -30,12 +30,13 @@ from . import output
 
 class TestCase(object):
   def __init__(self, suite, path, variant='default', flags=None,
-               dependency=None):
+               dependency=None, override_shell=None):
     self.suite = suite        # TestSuite object
     self.path = path          # string, e.g. 'div-mod', 'test-api/foo'
     self.flags = flags or []  # list of strings, flags specific to this test
     self.variant = variant    # name of the used testing variant
     self.dependency = dependency  # |path| for testcase that must be run first
+    self.override_shell = override_shell
     self.outcomes = set([])
     self.output = None
     self.id = None  # int, used to map result back to TestCase instance
@@ -44,7 +45,7 @@ class TestCase(object):
 
   def CopyAddingFlags(self, variant, flags):
     copy = TestCase(self.suite, self.path, variant, self.flags + flags,
-                    self.dependency)
+                    self.dependency, self.override_shell)
     copy.outcomes = self.outcomes
     return copy
 
@@ -55,15 +56,16 @@ class TestCase(object):
     """
     assert self.id is not None
     return [self.suitename(), self.path, self.variant, self.flags,
-            self.dependency, list(self.outcomes or []), self.id]
+            self.dependency, self.override_shell, list(self.outcomes or []),
+            self.id]
 
   @staticmethod
   def UnpackTask(task):
     """Creates a new TestCase object based on packed task data."""
     # For the order of the fields, refer to PackTask() above.
-    test = TestCase(str(task[0]), task[1], task[2], task[3], task[4])
-    test.outcomes = set(task[5])
-    test.id = task[6]
+    test = TestCase(str(task[0]), task[1], task[2], task[3], task[4], task[5])
+    test.outcomes = set(task[6])
+    test.id = task[7]
     test.run = 1
     return test
 
@@ -87,6 +89,11 @@ class TestCase(object):
   def GetLabel(self):
     return self.suitename() + "/" + self.suite.CommonTestName(self)
 
+  def shell(self):
+    if self.override_shell:
+      return self.override_shell
+    return self.suite.shell()
+
   def __getstate__(self):
     """Representation to pickle test cases.