Add back the test for the Rigid Body component

Adds back the test for the Rigid Body component that was removed when the scene grabbables support was removed (#319).

tests/test/tests/rigid-body.js

@@ -0,0 +1,65 @@
+const fs = require('fs');
+const path = require('path');
+const assert = require('assert');
+const utils = require('../utils.js');
+
+module.exports = {
+  description: 'can export rigid-body',
+  test: outDirPath => {
+    let gltfPath = path.resolve(outDirPath, 'rigid-body.gltf');
+    const asset = JSON.parse(fs.readFileSync(gltfPath));
+
+    assert.strictEqual(asset.extensionsUsed.includes('MOZ_hubs_components'), true);
+    assert.strictEqual(utils.checkExtensionAdded(asset, 'MOZ_hubs_components'), true);
+
+    const node = asset.nodes[0];
+    assert.strictEqual(utils.checkExtensionAdded(node, 'MOZ_hubs_components'), true);
+
+    const ext = node.extensions['MOZ_hubs_components'];
+    assert.deepStrictEqual(ext, {
+      "rigidbody":{
+        "type":"dynamic",
+        "disableCollision":false,
+        "collisionGroup":"objects",
+        "collisionMask":[
+          "objects",
+          "triggers",
+          "environment"
+        ],
+        "mass":1,
+        "linearDamping":0,
+        "angularDamping":0,
+        "linearSleepingThreshold":0.800000011920929,
+        "angularSleepingThreshold":1,
+        "angularFactor":[
+          1,
+          1,
+          1
+        ],
+        "gravity":[
+          0,
+          -9.800000190734863,
+          0
+        ]
+      },
+      "physics-shape":{
+        "type":"hull",
+        "fit":"all",
+        "halfExtents":{
+          "x":0.5,
+          "y":0.5,
+          "z":0.5
+        },
+        "minHalfExtent":0,
+        "maxHalfExtent":1000,
+        "sphereRadius":0.5,
+        "offset":{
+          "x":0,
+          "y":0,
+          "z":0
+        },
+        "includeInvisible":false
+      }
+    });
+  }
+};