Test spec paths are now relative to tool execution directory

This commit also normalizes the paths produced by the the test spec to
Unix style paths to increase portability of the file.

tools/test_api.py

@@ -2008,6 +2008,15 @@ def print_tests(tests, format="list", sort=True):
         print "Unknown format '%s'" % format
         sys.exit(1)
 
+def norm_relative_path(path, start):
+    """This function will create a normalized, relative path. It mimics the
+    python os.path.relpath function, but also normalizes a Windows-syle path
+    that use backslashes to a Unix style path that uses forward slashes."""
+    path = os.path.normpath(path)
+    path = os.path.relpath(path, start)
+    path = path.replace("\\", "/")
+    return path
+
 def build_tests(tests, base_source_paths, build_path, target, toolchain_name,
         options=None, clean=False, notify=None, verbose=False, jobs=1,
         macros=None, silent=False, report=None, properties=None,
@@ -2018,10 +2027,14 @@ def build_tests(tests, base_source_paths, build_path, target, toolchain_name,
     Returns a tuple of the build result (True or False) followed by the test
     build data structure"""
     
+    execution_directory = "."
+
+    base_path = norm_relative_path(build_path, execution_directory)
+    
     test_build = {
         "platform": target.name,
         "toolchain": toolchain_name,
-        "base_path": build_path,
+        "base_path": base_path,
         "baud_rate": 9600,
         "binary_type": "bootable",
         "tests": {}
@@ -2060,7 +2073,7 @@ def build_tests(tests, base_source_paths, build_path, target, toolchain_name,
         
         # Normalize the path
         if bin_file:
-            bin_file = os.path.normpath(bin_file)
+            bin_file = norm_relative_path(bin_file, execution_directory)
             
             test_build['tests'][test_name] = {
                 "binaries": [