[build_script.py] Add "install" subcommand

This builds upon the subcommand system added in
swiftlang#57, to add
an install command.

As that pull request describes, because there is no way to test
or install XCTest without also building the project, the current
Swift build script ends up building XCTest three times. This adds
an "install" subcommand that allows an already built XCTest to be
installed.

Author: modocache

build_script.py

@@ -25,16 +25,22 @@ def run(command):
     subprocess.check_call(command, shell=True)
 
 
+def _mkdirp(path):
+    """
+    Creates a directory at the given path if it doesn't already exist.
+    """
+    if not os.path.exists(path):
+        run("mkdir -p {}".format(path))
+
+
 def _build(args):
     """
     Build XCTest and place the built products in the given 'build_dir'.
     If 'test' is specified, also executes the 'test' subcommand.
     """
     swiftc = os.path.abspath(args.swiftc)
     build_dir = os.path.abspath(args.build_dir)
-
-    if not os.path.exists(build_dir):
-        run("mkdir -p {}".format(build_dir))
+    _mkdirp(build_dir)
 
     sourceFiles = [
                    "XCTAssert.swift",
@@ -59,32 +65,18 @@ def _build(args):
         "-module-link-name XCTest".format(swiftc, style_options, " ".join(sourcePaths), build_dir))
     run("{0} -emit-library {1}/XCTest.o -o {1}/libXCTest.so -lswiftGlibc -lswiftCore -lm".format(swiftc, build_dir))
 
-    # If we were given an install directive, perform installation
-    if args.module_path is not None and args.lib_path is not None:
-        module_path = os.path.abspath(args.module_path)
-        lib_path = os.path.abspath(args.lib_path)
-        run("mkdir -p {}".format(module_path))
-        run("mkdir -p {}".format(lib_path))
-
-        note("Performing installation into {} and {}".format(module_path, lib_path))
-
-        install_lib = "libXCTest.so"
-        install_mod_doc = "XCTest.swiftdoc"
-        install_mod = "XCTest.swiftmodule"
-
-        # These paths should have been created for us, unless we need to create new substructure.
-        cmd = ['cp', os.path.join(build_dir, install_lib), os.path.join(lib_path, install_lib)]
-        subprocess.check_call(cmd)
-
-        cmd = ['cp', os.path.join(build_dir, install_mod), os.path.join(module_path, install_mod)]
-        subprocess.check_call(cmd)
-        cmd = ['cp', os.path.join(build_dir, install_mod_doc), os.path.join(module_path, install_mod_doc)]
-        subprocess.check_call(cmd)
-
     if args.test:
         # Execute main() using the arguments necessary to run the tests.
         main(args=["test", "--swiftc", swiftc, build_dir])
 
+    # If --module-install-path and --library-install-path were specified,
+    # we also install the built XCTest products.
+    if args.module_path is not None and args.lib_path is not None:
+        # Execute main() using the arguments necessary for installation.
+        main(args=["install", build_dir,
+                   "--module-install-path", args.module_path,
+                   "--library-install-path", args.lib_path])
+
     note('Done.')
 
 
@@ -110,6 +102,34 @@ def _test(args):
                               tests_path=tests_path))
 
 
+def _install(args):
+    """
+    Install the XCTest.so, XCTest.swiftmodule, and XCTest.swiftdoc build
+    products into the given module and library paths.
+    """
+    build_dir = os.path.abspath(args.build_dir)
+    module_install_path = os.path.abspath(args.module_install_path)
+    library_install_path = os.path.abspath(args.library_install_path)
+
+    _mkdirp(module_install_path)
+    _mkdirp(library_install_path)
+
+    xctest_so = "libXCTest.so"
+    run("cp {} {}".format(
+        os.path.join(build_dir, xctest_so),
+        os.path.join(library_install_path, xctest_so)))
+
+    xctest_swiftmodule = "XCTest.swiftmodule"
+    run("cp {} {}".format(
+        os.path.join(build_dir, xctest_swiftmodule),
+        os.path.join(module_install_path, xctest_swiftmodule)))
+
+    xctest_swiftdoc = "XCTest.swiftdoc"
+    run("cp {} {}".format(
+        os.path.join(build_dir, xctest_swiftdoc),
+        os.path.join(module_install_path, xctest_swiftdoc)))
+
+
 def main(args=sys.argv[1:]):
     """
     The main entry point for this script. Based on the subcommand given,
@@ -196,11 +216,32 @@ def main(args=sys.argv[1:]):
         help="Path to the 'swiftc' compiler used to build and run the tests.",
         required=True)
 
+    install_parser = subparsers.add_parser(
+        "install",
+        description="Installs a built XCTest framework.")
+    install_parser.set_defaults(func=_install)
+    install_parser.add_argument(
+        "build_dir",
+        help="An absolute path to a directory containing a built XCTest.so, "
+             "XCTest.swiftmodule, and XCTest.swiftdoc.",
+        metavar="PATH")
+    install_parser.add_argument(
+        "-m", "--module-install-path",
+        help="Location at which to install XCTest.swiftmodule and "
+             "XCTest.swiftdoc. This directory will be created if it doesn't "
+             "already exist.",
+        metavar="PATH")
+    install_parser.add_argument(
+        "-l", "--library-install-path",
+        help="Location at which to install XCTest.so. This directory will be "
+             "created if it doesn't already exist.",
+        metavar="PATH")
+
     # Many versions of Python require a subcommand must be specified.
     # We handle this here: if no known subcommand (or none of the help options)
     # is included in the arguments, then insert the default subcommand
-    # argument.
-    if any([a in ["build", "test", "-h", "--help"] for a in args]):
+    # argument: 'build'.
+    if any([a in ["build", "test", "install", "-h", "--help"] for a in args]):
         parsed_args = parser.parse_args(args=args)
     else:
         parsed_args = parser.parse_args(args=["build"] + args)