Clean up dependencies installation symlinks on exit

The code used to install Arduino CLI, platform, and library dependencies does this by creating symlinks in the
appropriate locations on the runner. The files the script gathers via clone or download, are stored in a temporary folder
that is deleted when the script exits. This means the installation symlink for those files has no possible use after the
script finishes.

This particular pollution of the runner's environment is resolved by also registering a call to delete on exit as each
symlink is created.

.github/workflows/test-integration.yml

@@ -114,6 +114,95 @@ jobs:
       report-artifact-name: ${{ steps.report-artifact-name.outputs.report-artifact-name }}
 
 
+  multiple-steps:
+    name: multiple-steps (${{ matrix.board.source-type }})
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+
+      matrix:
+        board:
+          - source-type: manager
+            fqbn: arduino:avr:uno
+            platforms: |
+              - name: arduino:avr
+                version: 1.8.3
+            libraries: |
+              - name: Servo
+                version: 1.1.7
+          - source-type: path
+            fqbn: arduino:avr:uno
+            platforms: |
+              - name: arduino:avr
+                version: 1.8.3
+              - source-path: extras/ArduinoCore-avr
+                name: arduino:avr
+            libraries: |
+              - source-path: ./
+                name: Servo
+          - source-type: repo
+            fqbn: arduino:avr:uno
+            platforms: |
+              - name: arduino:avr
+                version: 1.8.3
+              - source-url: https://github.com/arduino/ArduinoCore-avr.git
+                name: arduino:avr
+                version: 1.8.3
+            libraries: |
+              - source-url: https://github.com/arduino-libraries/Servo.git
+                name: Servo
+                version: 1.1.7
+          - source-type: archive
+            fqbn: arduino:avr:uno
+            platforms: |
+              - name: arduino:avr
+                version: 1.8.3
+              - source-url: https://github.com/arduino/ArduinoCore-avr/archive/refs/tags/1.8.3.zip
+                name: arduino:avr
+            libraries: |
+              - source-url: https://github.com/arduino-libraries/Servo/archive/refs/tags/1.1.7.zip
+                name: Servo
+
+    steps:
+      - name: Checkout library
+        uses: actions/checkout@v2
+        with:
+          repository: arduino-libraries/Servo
+          ref: 1.1.7
+
+      - name: Checkout platform
+        if: matrix.board.source-type == 'path'
+        uses: actions/checkout@v2
+        with:
+          repository: arduino/ArduinoCore-avr
+          ref: 1.8.3
+          path: extras/ArduinoCore-avr
+
+      - name: Checkout local repo
+        uses: actions/checkout@v2
+        with:
+          path: extras/compile-sketches
+
+      - name: Run action
+        # Use action from local path
+        uses: ./extras/compile-sketches
+        with:
+          platforms: ${{ matrix.board.platforms }}
+          fqbn: ${{ matrix.board.fqbn }}
+          libraries: ${{ matrix.board.libraries }}
+          sketch-paths: |
+            - examples/Sweep
+
+      - name: Run action again
+        uses: ./extras/compile-sketches
+        with:
+          platforms: ${{ matrix.board.platforms }}
+          fqbn: ${{ matrix.board.fqbn }}
+          libraries: ${{ matrix.board.libraries }}
+          sketch-paths: |
+            - examples/Sweep
+
   check-sketches-reports:
     needs: all-inputs
     runs-on: ubuntu-latest

compilesketches/compilesketches.py

@@ -1,3 +1,4 @@
+import atexit
 import contextlib
 import enum
 import json
@@ -576,6 +577,10 @@ def install_from_path(self, source_path, destination_parent_path, destination_na
 
         destination_path.symlink_to(target=source_path, target_is_directory=source_path.is_dir())
 
+        # Remove the symlink on script exit. The source path files added by the script are stored in a temporary folder
+        # which is deleted on exit, so the symlink will serve no purpose.
+        atexit.register(destination_path.unlink)
+
     def install_platforms_from_repository(self, platform_list):
         """Install libraries by cloning Git repositories