Add workdir() method to UnixBuild (#462)

Author: brettcannon

master/custom/factories.py

@@ -67,6 +67,13 @@ class UnixBuild(BaseBuild):
     test_environ = {}
     build_out_of_tree = False
 
+    def workdir(self, *parts):
+        """Calculate the working dir to change to.
+
+        Designed to be used with the `workdir` argument to e.g. ShellCommand.
+        """
+        return os.path.join("build", *parts)
+
     def setup(self, parallel, branch, test_with_PTY=False, **kwargs):
         out_of_tree_dir = "build_oot"
 
@@ -82,7 +89,7 @@ def setup(self, parallel, branch, test_with_PTY=False, **kwargs):
 
         if self.build_out_of_tree:
             configure_cmd = "../configure"
-            oot_kwargs = {'workdir': os.path.join("build", out_of_tree_dir)}
+            oot_kwargs = {'workdir': self.workdir(out_of_tree_dir)}
         else:
             configure_cmd = "./configure"
             oot_kwargs = {}
@@ -686,7 +693,7 @@ def setup(self, parallel, branch, test_with_PTY=False, **kwargs):
         assert self.host is not None, "Must set self.host on cross builds"
 
         out_of_tree_dir = "build_oot"
-        oot_dir_path = os.path.join("build", out_of_tree_dir)
+        oot_dir_path = self.workdir(out_of_tree_dir)
         oot_build_path = os.path.join(oot_dir_path, "build")
         oot_host_path = os.path.join(oot_dir_path, "host")
 
@@ -873,7 +880,7 @@ def __init__(self, source, *, extra_tags=[], **kwargs):
 
     def setup(self, parallel, branch, test_with_PTY=False, **kwargs):
         wasi_py = "Tools/wasm/wasi.py"
-        host_path = "build/cross-build/wasm32-wasi"
+        host_path = self.workdir("cross-build", "wasm32-wasi")
 
         # Build Python
         build_configure = ["python3", wasi_py, "configure-build-python"]