Add CI tests, run VARNA tests only if java is installed (#8)

* Add CI github workflow

* Only run VARNA tests if java executable can be found

* Add CI badge to README

.github/workflows/CI.yml

@@ -0,0 +1,41 @@
+name: CI
+on:
+  push:
+    branches:
+      - main
+    tags: ['*']
+  pull_request:
+concurrency:
+  # Skip intermediate builds: always.
+  # Cancel intermediate builds: only if it is a pull request build.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+jobs:
+  test:
+    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        version:
+          - '1.6'
+          - '1'
+        os:
+          - ubuntu-latest
+          - macOS-latest
+          - windows-latest
+        arch:
+          - x64
+    steps:
+      - uses: actions/checkout@v2
+      - uses: julia-actions/setup-julia@v1
+        with:
+          version: ${{ matrix.version }}
+          arch: ${{ matrix.arch }}
+      - uses: julia-actions/cache@v1
+      - uses: julia-actions/julia-buildpkg@v1
+      - uses: julia-actions/julia-runtest@v1
+      - uses: julia-actions/julia-processcoverage@v1
+      - uses: codecov/codecov-action@v2
+        with:
+          files: lcov.info

README.md

@@ -1,5 +1,7 @@
 # PlotRNA.jl
 
+[![Build Status](https://github.com/marcom/PlotRNA.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/marcom/PlotRNA.jl/actions/workflows/CI.yml?query=branch%3Amain)
+
 Plot nucleic acid secondary structures with Julia.
 
 There are currently four different backends:

test/runtests.jl

@@ -7,7 +7,11 @@ showtestset() = println(" "^(2 * Test.get_testset_depth()), "testing ",
 @testset verbose=true "PlotRNA" begin
     showtestset()
     include("plot_structure.jl")
-    include("varna.jl")
+    if isnothing(Sys.which("java"))
+        @warn "Can't find java executable, skipping VARNA tests"
+    else
+        include("varna.jl")
+    end
     include("r2r.jl")
     include("uniplot.jl")
     include("plot_structure_makie.jl")