Remove Travis CI

[IshaanDesai]

This PR removes Travis CI as the mock tests run in the CI are now run as a GitHub Actions job

[BenjaminRodenberg]

Removing this test is good. As far as I undestand the corresponding github actions test is this one:

python-bindings/.github/workflows/build-and-test.yml

Lines 71 to 96 in 6e54396

	setup_test:
	name: Run setup test
	runs-on: ubuntu-latest
	container: precice/ci-ubuntu-1804
	steps:
	- name: Checkout Repository
	uses: actions/checkout@v2
	- name: Install & upgrade pip3
	run: |
	apt-get -yy update
	apt-get install -y python3-pip
	rm -rf /var/lib/apt/lists/*
	pip3 install --upgrade --user pip
	- name: Checkout precice and make required files discoverable
	run: |
	git clone https://github.com/precice/precice.git precice-core
	mkdir -p precice
	cp precice-core/src/precice/SolverInterface.hpp precice/SolverInterface.hpp
	- name: Install dependencies
	run: |
	pip3 install --user toml
	python3 -c 'import toml; c = toml.load("pyproject.toml"); print("\n".join(c["build-system"]["requires"]))' | pip3 install -r /dev/stdin
	- name: Run setup test
	run: |
	export CFLAGS=-I$GITHUB_WORKSPACE
	python3 setup.py test

I still see a minor problem here: The old test on travis uses a generic docker image as basis (probably some ubuntu?). The github-actions-based test uses precice/ci-ubuntu-1804. If possible, please use ubuntu:20.04 or a similarly simple image as basis, since otherwise this contradicts the idea of mocking a bit. You can use the fenics-adapter mock test as a reference. Here, container: quay.io/fenicsproject/stable:current provides fenics, but all the other dependencies of preCICE and preCICE itself can be ignored and are therefore not present.

[IshaanDesai]

I see the problem with using the container precice/ci-ubuntu-1804, it does indeed violate the broad mock testing principle. But in the test/SolverInterface.cpp we do import the original preCICE header file here:

python-bindings/test/SolverInterface.cpp

Line 1 in 6e54396

#include "precice/SolverInterface.hpp"

In my understanding this requires the container to have the preCICE compiled or at least the code be present there. Is this correct? If the GitHub action is run on just a ubuntu container then the following error is seen:

| /home/desaiin/python-bindings/cyprecice/cyprecice.cpp:671:10: fatal error: precice/SolverInterface.hpp: No such file or directory
|   671 | #include "precice/SolverInterface.hpp"
|       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| compilation terminated.
| error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
[Build and Test/Run setup test]   ❌  Failure - Run setup test

[BenjaminRodenberg]

I see the problem with using the container precice/ci-ubuntu-1804, it does indeed violate the broad mock testing principle. But in the test/SolverInterface.cpp we do import the original preCICE header file here:

python-bindings/test/SolverInterface.cpp

Line 1 in 6e54396

#include "precice/SolverInterface.hpp"

In my understanding this requires the container to have the preCICE compiled or at least the code be present there. Is this correct? If the GitHub action is run on just a ubuntu container then the following error is seen:

| /home/desaiin/python-bindings/cyprecice/cyprecice.cpp:671:10: fatal error: precice/SolverInterface.hpp: No such file or directory
|   671 | #include "precice/SolverInterface.hpp"
|       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| compilation terminated.
| error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
[Build and Test/Run setup test]   ❌  Failure - Run setup test

precice/SolverInterface.hpp is needed. Yes. But the rest of preCICE is not needed. The idea here is the following:

• Use the real precice/SolverInterface.hpp to ensure that the interface that we are testing is the real preCICE interface
• Use a fake SolverInterface.cpp as implementation.

The important part is here:

python-bindings/.github/workflows/build-and-test.yml

Lines 84 to 88 in 6e54396

	- name: Checkout precice and make required files discoverable
	run: |
	git clone https://github.com/precice/precice.git precice-core
	mkdir -p precice
	cp precice-core/src/precice/SolverInterface.hpp precice/SolverInterface.hpp

We clone precice, since we need precice/SolverInterface.hpp and then move it to a location, where the compiler can discover it (precice/SolverInterface.hpp). preCICE itself is never installed, all other header files are missing.

If we then want to build test, we do not link against the real preCICE (it does not exist on the system), but just provide the fake SolverInterface.cpp as sources:

python-bindings/setup.py

Lines 72 to 76 in 6e54396

	if not is_test:
	link_args.append("-lprecice")
	if is_test:
	bindings_sources.append(os.path.join(PYTHON_BINDINGS_PATH, "test",
	"SolverInterface.cpp"))

I hope this explanation helps. It's not documented well and I assume must be very confusing, if you don't know where you have to look.

[BenjaminRodenberg]

Looks good. I will quickly check and apply the minor things I've spotted and then directly merge this PR.

[BenjaminRodenberg]

Related to #101: We should be able to remove the mpi part here.

But for the current state everything is fine.

[IshaanDesai]

Okay, will keep this dependency problem in mind.