Add minimal test for regex.grep.

test/grep.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+
+# Copyright 2023 René Ferdinand Rivera Morell
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE.txt or https://www.bfgroup.xyz/b2/LICENSE.txt)
+
+import os
+import BoostBuild
+
+t = BoostBuild.Tester(pass_toolset=False)
+
+t.write("Jamroot", """
+import regex ;
+local a = [ regex.grep . : *.*pp : "#(include) <([^>]+)>" ] ;
+while $(a)
+{
+    ECHO $(a[1]:D=) $(a[2]) ;
+    a = $(a[3-]) ;
+}
+local b = [ regex.grep . : *.*pp : "#(include) <([^>]+)>" : 1 2 ] ;
+while $(b)
+{
+    ECHO $(b[1]:D=) $(b[2-3]) ;
+    b = $(b[4-]) ;
+}
+EXIT : 0 ;
+""")
+t.write("a.cpp", """
+#include <b.hpp>
+""")
+t.write("b.hpp", """
+#include <a>
+""")
+
+t.run_build_system()
+t.expect_output_lines([
+    "a.cpp #include <b.hpp>",
+    "b.hpp #include <a>",
+    "a.cpp include b.hpp",
+    "b.hpp include a",
+])
+t.expect_nothing_more()
+
+t.cleanup()

test/test_all.py

@@ -306,6 +306,7 @@ def reorder_tests(tests, first_test):
          "flags",
          "generator_selection",
          "generators_test",
+         "grep",
          "implicit_dependency",
          "indirect_conditional",
          "inherit_toolset",