add option 'update'

.github/workflows/test.yml

@@ -36,3 +36,23 @@ jobs:
       with:
         msystem: ${{ matrix.task }}
     - run: msys2do ./test.sh
+
+  update:
+    strategy:
+      matrix:
+        task: [ MSYS, MINGW64, MINGW32 ]
+    runs-on: windows-latest
+    steps:
+    - uses: actions/checkout@v1
+    - name: build action
+      shell: bash
+      run: |
+        npm ci
+        npm run build
+        rm -rf node_modules
+    - name: run action
+      uses: ./
+      with:
+        update: True
+        msystem: ${{ matrix.task }}
+    - run: msys2do ./test.sh

README.md

@@ -11,6 +11,10 @@ The latest tarball available at [repo.msys2.org/distrib/x86_64](http://repo.msys
   - run: msys2do uname -a
 ```
 
+### Options
+
+#### msystem
+
 By default, `MSYSTEM` is set to `MINGW64`. However, an optional parameter named `msystem` is supported, which expects `MSYS`, `MINGW64` or `MING32`. For example:
 
 ```yaml
@@ -31,3 +35,13 @@ Furthermore, the environment variable can be overriden. This is useful when mult
       set MSYSTEM=MINGW64
       msys2do <command to test the package>
 ```
+
+#### update
+
+By default, the installation is not updated; hence package versions are those of the installation tarball. By setting option `update` to `true`, the action will execute `pacman -Syu --no-confirm`:
+
+```yaml
+  - uses: numworks/setup-msys2@v1
+    with:
+      update: true
+```

action.yml

@@ -6,6 +6,10 @@ inputs:
     description: 'Variant of the environment to set by default: MSYS, MINGW32 or MINGW64'
     required: false
     default: 'MINGW64'
+  update:
+    description: 'Update MSYS2 installation through pacman'
+    required: false
+    default: false
 runs:
   using: 'node12'
   main: 'index.js'

index.js

@@ -45,7 +45,11 @@ async function run() {
 
     core.startGroup('Starting MSYS2 for the first time...');
       // For some reason, `msys2do` does not work
-      await exec.exec(`"${cmd}"`, ['uname', '-a']);
+      await exec.exec(`"${cmd}"`, (core.getInput('update') == 'true') ?
+        ['pacman', '-Syu', '--noconfirm']
+        :
+        ['uname', '-a']
+      );
     core.endGroup();
   }
   catch (error) {