Lint podspec on all pull requests

- We recently let a couple of issues slip through code review becase we don't lint our podspec on pull requests since the task takes too long (about half an hour). To prevent this from happening again, this PR adds 2 new CI jobs that lint default and other subspecs on all PRs. By splitting into 2 tasks, the impact on total CI time should be mitigated somewhat. There is still a master-only task that lint all subspecs as the last line of defense in case the 2 new tasks miss any.

.github/workflows/ci-pull-requests-only.yml

@@ -0,0 +1,26 @@
+name: CI (pull-requests-only jobs)
+
+on:
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  buildsh:
+    env:
+        DEVELOPER_DIR: /Applications/Xcode_11.app/Contents/Developer
+    strategy:
+      matrix:
+        mode: [cocoapods-lint-default-subspecs, cocoapods-lint-other-subspecs]
+        include:
+          - mode: cocoapods-lint-default-subspecs
+            name: Verify that default subspecs lint
+          - mode: cocoapods-lint-other-subspecs
+            name: Verify that other subspecs lint
+    name: ${{ matrix.name }}
+    runs-on: macOS-latest
+    steps:
+    - name: Checkout the Git repository
+      uses: actions/checkout@v1
+    - name: Run build script
+      run: ./build.sh ${{ matrix.mode }}

.github/workflows/ci.yml

@@ -32,4 +32,4 @@ jobs:
     - name: Checkout the Git repository
       uses: actions/checkout@v1
     - name: Run build script
-      run: ./build.sh ${{ matrix.mode }}
+      run: ./build.sh ${{ matrix.mode }}

build.sh

@@ -56,6 +56,11 @@ function build_example {
     fi
 }
 
+# Lint subspec
+function lint_subspec {
+    set -o pipefail && pod env && pod lib lint --allow-warnings --subspec="$1"
+}
+
 function cleanup {
     # remove all Pods directories
     find . -name Pods -type d -exec rm -rf {} +
@@ -216,6 +221,28 @@ cocoapods-lint|all)
     success="1"
     ;;
 
+cocoapods-lint-default-subspecs)
+    echo "Verifying that default subspecs lint."
+
+    for subspec in 'Core' 'PINRemoteImage' 'Video' 'MapKit' 'AssetsLibrary' 'Photos'; do
+        echo "Verifying that $subspec subspec lints."
+
+        lint_subspec $subspec
+    done
+    success="1"
+    ;;
+
+cocoapods-lint-other-subspecs)
+    echo "Verifying that other subspecs lint."
+
+    for subspec in 'IGListKit' 'Yoga' 'TextNode2'; do
+        echo "Verifying that $subspec subspec lints."
+
+        lint_subspec $subspec
+    done
+    success="1"
+    ;;
+
 carthage|all)
     echo "Verifying carthage works."