[TestBase.runCmd] Better error message when runCmd fails.

Summary:
Before:
    AssertionError: False is not True : Process is launched successfully

After:
    AssertionError: False is not True : Command 'run a.out' failed.
    >>> error: invalid target, create a target using the 'target create' command
    >>> Process could not be launched successfully

Reviewers: clayborg

Reviewed By: clayborg

Subscribers: lldb-commits, vharron

Differential Revision: http://reviews.llvm.org/D9948

llvm-svn: 238363
diff --git a/lldb/test/expression_command/call-function/TestCallStopAndContinue.py b/lldb/test/expression_command/call-function/TestCallStopAndContinue.py
index 0814c40..aa0e5327 100644
--- a/lldb/test/expression_command/call-function/TestCallStopAndContinue.py
+++ b/lldb/test/expression_command/call-function/TestCallStopAndContinue.py
@@ -42,7 +42,7 @@
         # Some versions of GCC encode two locations for the 'return' statement in main.cpp
         lldbutil.run_break_set_by_file_and_line (self, "main.cpp", self.line, num_expected_locations=-1, loc_exact=True)
 
-        self.runCmd("run", RUN_SUCCEEDED)
+        self.runCmd("run", RUN_FAILED)
 
         lldbutil.run_break_set_by_file_and_line (self, "main.cpp", self.func_line, num_expected_locations=-1, loc_exact=True)