Simple CI test integration for Wasm

Intentionally skipping coverage here, as Wasm doesn't cover everything.

.gitattributes

@@ -1,2 +1,2 @@
 src/libvips/* linguist-vendored
-build/** linguist-generated
+build/Release/sharp-emscripten-wasm32.node.* linguist-generated

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
   CI:
     permissions:
       contents: write # for npx prebuild to make release
-    name: ${{ matrix.container || matrix.os }} - Node.js ${{ matrix.nodejs_version }} ${{ matrix.nodejs_arch }} ${{ matrix.prebuild && '- prebuild' }}
+    name: ${{ matrix.container || matrix.os }} - Node.js ${{ matrix.nodejs_version }} ${{ matrix.addon_arch || matrix.nodejs_arch }} ${{ matrix.prebuild && '- prebuild' }}
     runs-on: ${{ matrix.os }}
     container: ${{ matrix.container }}
     strategy:
@@ -31,6 +31,9 @@ jobs:
             container: node:16-alpine3.12
           - os: ubuntu-22.04
             container: node:18-alpine3.14
+          - os: ubuntu-22.04
+            container: node:18-alpine3.14
+            addon_arch: wasm32
           - os: macos-11
             nodejs_version: 14
             prebuild: true
@@ -95,9 +98,17 @@ jobs:
         if: matrix.container
         run: chown root.root .
       - name: Install
+        if: matrix.addon_arch != 'wasm32'
         run: npm install --build-from-source --unsafe-perm
+      - name: Install (WebAssembly)
+        if: matrix.addon_arch == 'wasm32'
+        run: npm install --ignore-scripts
       - name: Test
+        if: matrix.addon_arch != 'wasm32'
         run: npm test
+      - name: Test (WebAssembly)
+        if: matrix.addon_arch == 'wasm32'
+        run: npx --arch=wasm32 mocha
       - name: Prebuild
         if: matrix.prebuild && startsWith(github.ref, 'refs/tags/')
         env:

test/unit/platform.js

@@ -17,23 +17,19 @@ describe('Platform-detection', function () {
     }
   });
 
-  // Don't let outer npm_config_* variables leak into a platform test.
-  beforeEach(() => {
+  function cleanupEnv () {
     for (const key of npmConfigKeys()) {
       delete process.env[key];
     }
-  });
+  }
+
+  // Don't let outer npm_config_* variables leak into a platform test.
+  beforeEach(cleanupEnv);
 
   // Restore the original config for other test suites.
   after(() => {
-    for (const key of npmConfigKeys()) {
-      const value = npmEnv[key];
-      if (value === undefined) {
-        delete process.env[key];
-      } else {
-        process.env[key] = value;
-      }
-    }
+    cleanupEnv();
+    Object.assign(process.env, npmEnv);
   });
 
   it('Can override arch with npm_config_arch', function () {