bazel: test GUI on github request use-case

These instructions are waiting for `:openroad` bazel targets to be OpenROAD
built with GUI support and `:openroad-cli` to be OpenROAD built
with CLI only support.

Signed-off-by: Øyvind Harboe <[email protected]>

Author: oharboe

docs/user/Bazel.md

@@ -339,3 +339,17 @@ Now start the bisection as usual with a bad and good commit from the above list:
 Use `git bisect --skip` if the version does not build or otherwise should not be tested.
 
 OpenSTA has an additional challenge in that only the https://github.com/The-OpenROAD-Project/OpenSTA fork has the Bazel BUILD file. To bisect the https://github.com/parallaxsw/OpenSTA branch, check out the branch you want, then check out BUILD from the fork and do a `git reset HEAD`. This will leave BUILD as a local file, because it is not in the upstream repository and bisection can be done on the upstream master branch.
+
+## Testing the GUI with gcd on a pull request by number
+
+This will:
+
+- fetch and checkout pull request 7856
+- build OpenROAD
+- run bazel-orfs flow on gcd
+- create a /tmp/gcd folder with the ORFS project. `bazelisk run test/orfs/gcd:gcd_final` run alone would create the /tmp/gcd folder and the arguments. The arguments after `--` are forwarded to the /tmp/gcd/make script that invokes make with the gcd ORFS project set up in /tmp/gcd/_main/config.mk.
+- launch the GUI opening gui_final gcd
+
+    $ git fetch origin pull/7856/head
+    $ git checkout FETCH_HEAD
+    $ bazelisk run test/orfs/gcd:gcd_final /tmp/gcd -- gui_final