fix preprocess_pragmas and add tests (#2038)

tools/tests/README

@@ -0,0 +1 @@
+This folder contains tests for the tools living in this repo.

tools/tests/test_preprocess_pragmas.py

@@ -0,0 +1,107 @@
+import difflib
+from pathlib import Path
+import subprocess
+
+
+# change to True to print output source on failed tests
+PRINT_FAILED_OUTPUT = False
+
+PREPROCESS_PRAGMAS_P = Path("tools/preprocess_pragmas")
+
+
+def fake_struct(pragma_line, i):
+    return f"struct increment_block_number_{pragma_line:05}_{i:03};"
+
+
+def fake_structs(pragma_line, amount):
+    return "\n".join(fake_struct(pragma_line, i) for i in range(amount))
+
+
+data = {
+    "test_noarg": (
+        "gc-us",
+        "source.c",
+        """\
+abc
+#pragma increment_block_number
+def
+""",
+        f"""\
+abc
+{fake_structs(2, 256)}
+#line 3 "source.c"
+def
+""",
+    ),
+    "test_one_arg_match": (
+        "gc-us",
+        "source.c",
+        """\
+abc
+#pragma increment_block_number "gc-us:17"
+def
+""",
+        f"""\
+abc
+{fake_structs(2, 17)}
+#line 3 "source.c"
+def
+""",
+    ),
+    "test_one_arg_no_match": (
+        "gc-us",
+        "source.c",
+        """\
+abc
+#pragma increment_block_number "gc-us-mq:17"
+def
+""",
+        f"""\
+abc
+{fake_structs(2, 256)}
+#line 3 "source.c"
+def
+""",
+    ),
+    "test_several_args": (
+        "gc-us",
+        "source.c",
+        """\
+abc
+#pragma increment_block_number "gc-us-mq:200 gc-us:250"
+def
+""",
+        f"""\
+abc
+{fake_structs(2, 250)}
+#line 3 "source.c"
+def
+""",
+    ),
+}
+
+for test_name, (version, filename, source_in, expected_source_out) in data.items():
+    p = subprocess.Popen(
+        [str(PREPROCESS_PRAGMAS_P), version, filename],
+        stdin=subprocess.PIPE,
+        stdout=subprocess.PIPE,
+        encoding="UTF-8",
+    )
+    source_out, _ = p.communicate(input=source_in)
+    if p.returncode != 0:
+        print(f"{PREPROCESS_PRAGMAS_P} ended with {p.returncode} on {test_name}")
+        exit(1)
+    if source_out != expected_source_out:
+        print(f"failed test {test_name}")
+        if PRINT_FAILED_OUTPUT:
+            print(source_out)
+        for l in difflib.unified_diff(
+            expected_source_out.splitlines(),
+            source_out.splitlines(),
+            "expected output",
+            "actual output",
+        ):
+            print(l)
+        exit(1)
+
+print("all tests ok")