Enable R package caching (#2)

* Based on usethis check-full.yaml example.

.github/workflows/ci-cd.yml

@@ -6,16 +6,34 @@ jobs:
   CI-CD:
     runs-on: ubuntu-latest
     steps:
+
       - uses: actions/checkout@v2
+
       - uses: r-lib/actions/setup-r@master
+
+      - name: Query dependencies
+        run: |
+          install.packages("remotes"")
+          saveRDS(remotes::dev_package_deps(dependencies = TRUE), "depends.Rds", version = 2)
+        shell: Rscript {0}
+
+      - name: Cache R packages
+        uses: actions/cache@v1
+        with:
+          path: ${{ env.R_LIBS_USER }}
+          key: ${{ runner.os }}-r-${{ hashFiles('depends.Rds') }}
+          restore-keys: ${{ runner.os }}-r-
+
       - name: Install dependencies
         run: |
-          install.packages(c("remotes", "rcmdcheck", "rsconnect"))
           remotes::install_deps(dependencies = TRUE)
+          remotes::install_cran("rcmdcheck")
         shell: Rscript {0}
-      - name: R CMD check
-        run: rcmdcheck::rcmdcheck(args = "--no-manual", error_on = "error")
+
+      - name: Check
+        run: rcmdcheck::rcmdcheck(args = "--no-manual", error_on = "warning", check_dir = "check")
         shell: Rscript {0}
+
       - name: Deploy to shinyapps.io
         if: github.ref == 'refs/heads/feature/2-gh-actions-ci-cd'
         env: