compile_and_test_for_boards: Add no-compile flag

Since we have a no-test flag that prevents executing tests, I think
a no-compile flag is a nice compliment. Why? Well if I want to use
this script for running multiple boards at the same time, RIOT is
not so great handling parallel compile steps with conflicts on
lockfiles happening, mostly due to packages. With this I can
compile a list of boards sequentially, then flash and run tests
in parallel, skipping the compile step.

dist/tools/compile_and_test_for_board/compile_and_test_for_board.py

@@ -35,7 +35,8 @@ Usage
 ```
 usage: compile_and_test_for_board.py [-h] [--applications APPLICATIONS]
                                      [--applications-exclude APPLICATIONS_EXCLUDE]
-                                     [--no-test] [--with-test-only]
+                                     [--no-test] [--no-compile]
+                                     [--with-test-only]
                                      [--loglevel {debug,info,warning,error,fatal,critical}]
                                      [--incremental] [--clean-after]
                                      [--compile-targets COMPILE_TARGETS]
@@ -61,12 +62,14 @@ optional arguments:
                         applications. Also applied after "--applications".
                         (default: None)
   --no-test             Disable executing tests (default: False)
+  --no-compile          Disable compiling tests, this assumes the compilation
+                        was already done (default: False)
   --with-test-only      Only compile applications that have a test (default:
                         False)
   --loglevel {debug,info,warning,error,fatal,critical}
                         Python logger log level (default: info)
-  --incremental         Do not rerun successful compilation and tests
-                        (default: False)
+  --incremental         Do not rerun successful compilation and tests (default:
+                        False)
   --clean-after         Clean after running each test (default: False)
   --compile-targets COMPILE_TARGETS
                         List of make targets to compile (default: clean all)
@@ -360,6 +363,7 @@ class RIOTApplication:
     def compilation_and_test(
         self,
         clean_after=False,
+        runcompile=True,
         runtest=True,
         incremental=False,
         jobs=False,
@@ -408,13 +412,13 @@ class RIOTApplication:
 
         # Run compilation and flash+test
         # It raises ErrorInTest on error which is handled outside
-
-        compilation_cmd = list(self.COMPILE_TARGETS)
-        if jobs is not None:
-            compilation_cmd += ["--jobs"]
-            if jobs:
-                compilation_cmd += [str(jobs)]
-        self.make_with_outfile("compilation", compilation_cmd)
+        if runcompile:
+            compilation_cmd = list(self.COMPILE_TARGETS)
+            if jobs is not None:
+                compilation_cmd += ["--jobs"]
+                if jobs:
+                    compilation_cmd += [str(jobs)]
+            self.make_with_outfile("compilation", compilation_cmd)
         if clean_after:
             self.clean_intermediates()
 
@@ -670,6 +674,12 @@ PARSER.add_argument(
 PARSER.add_argument(
     "--no-test", action="store_true", default=False, help="Disable executing tests"
 )
+PARSER.add_argument(
+    "--no-compile",
+    action="store_true",
+    default=False,
+    help="Disable compiling tests, this assumes the compilation was already done",
+)
 PARSER.add_argument(
     "--with-test-only",
     action="store_true",
@@ -783,6 +793,7 @@ def main(args):
     errors = [
         app.run_compilation_and_test(
             clean_after=args.clean_after,
+            runcompile=not args.no_compile,
             runtest=not args.no_test,
             incremental=args.incremental,
             jobs=args.jobs,

dist/tools/compile_and_test_for_board/tests/test_compile_and_test_for_board.py

@@ -1,10 +1,14 @@
 """Test compile_and_test_for_board script."""
 
 import subprocess
-
+import re
 import compile_and_test_for_board
 
 
+def _clean(my_str):
+    return re.sub(r'\s+', ' ', my_str)
+
+
 def test_help_message():
     """Verify that the help message is in the script documentation."""
     script = 'compile_and_test_for_board.py'
@@ -14,5 +18,7 @@ def test_help_message():
     help_msg = help_bytes.decode('utf-8')
 
     docstring = compile_and_test_for_board.__doc__
-
-    assert help_msg in docstring, "Help message not in the documentation"
+    assert _clean(help_msg) in _clean(docstring), ("Help message not in the",
+                                                   "documentation")
+    help_msg += "garbage"
+    assert help_msg not in docstring, ("Negative help message test failed.")