tests: Add a coverage test for printing the parse-tree.

tests/cmdline/cmd_parsetree.py

+# cmdline: -v -v -v
+# test printing of the parse-tree
+
+for i in ():
+    pass
+a = None
+b = 'str'
+c = 'a very long str that will not be interned'
+d = b'bytes'
+e = b'a very long bytes that will not be interned'
+f = 123456789012345678901234567890

tests/cmdline/cmd_parsetree.py.exp

+----------------
+[   4] rule(2) (n=8)
+         tok(5)
+[   4]   rule(78) (n=4)
+           id(i)
+[   4]     rule(131) (n=1)
+             NULL
+[   5]     rule(42) (n=0)
+           NULL
+[   6]   rule(32) (n=2)
+           id(a)
+           tok(15)
+[   7]   rule(32) (n=2)
+           id(b)
+           str(str)
+[   8]   rule(32) (n=2)
+           id(c)
+[   8]     literal str(a very long str that will not be interned)
+[   9]   rule(32) (n=2)
+           id(d)
+           bytes(bytes)
+[  10]   rule(32) (n=2)
+           id(e)
+[  10]     literal bytes(a very long bytes that will not be interned)
+[  11]   rule(32) (n=2)
+           id(f)
+[  11]     literal \.\+
+----------------
+File cmdline/cmd_parsetree.py, code block '<module>' (descriptor: \.\+, bytecode @\.\+ bytes)
+Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
+########
+\.\+5b
+arg names:
+(N_STATE 2)
+(N_EXC_STACK 0)
+  bc=-1 line=1
+  bc=0 line=4
+  bc=9 line=5
+  bc=12 line=6
+  bc=16 line=7
+  bc=22 line=8
+  bc=27 line=9
+  bc=32 line=10
+  bc=37 line=11
+00 BUILD_TUPLE 0
+02 GET_ITER
+03 FOR_ITER 12
+06 STORE_NAME i
+09 JUMP 3
+12 LOAD_CONST_NONE
+13 STORE_NAME a
+16 LOAD_CONST_STRING 'str'
+19 STORE_NAME b
+22 LOAD_CONST_OBJ \.\+
+24 STORE_NAME c
+27 LOAD_CONST_OBJ \.\+
+29 STORE_NAME d
+32 LOAD_CONST_OBJ \.\+
+34 STORE_NAME e
+37 LOAD_CONST_OBJ \.\+
+39 STORE_NAME f
+42 LOAD_CONST_NONE
+43 RETURN_VALUE
+mem: total=\\d\+, current=\\d\+, peak=\\d\+
+stack: \\d\+ out of \\d\+
+GC: total: \\d\+, used: \\d\+, free: \\d\+
+ No. of 1-blocks: \\d\+, 2-blocks: \\d\+, max blk sz: \\d\+, max free sz: \\d\+

tests/feature_check/coverage.py

+try:
+    extra_coverage
+    print('coverage')
+except NameError:
+    print('no')

tests/run-tests

@@ -208,6 +208,7 @@ def run_tests(pyb, tests, args):
 
     upy_byteorder = run_micropython(pyb, args, 'feature_check/byteorder.py')
     has_complex = run_micropython(pyb, args, 'feature_check/complex.py') == b'complex\n'
+    has_coverage = run_micropython(pyb, args, 'feature_check/coverage.py') == b'coverage\n'
     cpy_byteorder = subprocess.check_output([CPYTHON3, 'feature_check/byteorder.py'])
     skip_endian = (upy_byteorder != cpy_byteorder)
 
@@ -225,6 +226,9 @@ def run_tests(pyb, tests, args):
         skip_tests.add('float/true_value.py')
         skip_tests.add('float/types.py')
 
+    if not has_coverage:
+        skip_tests.add('cmdline/cmd_parsetree.py')
+
     # Some tests shouldn't be run on a PC
     if pyb is None:
         # unix build does not have the GIL so can't run thread mutation tests