Unit tests (#112)

* Added unit tests for js witness calculation and proof generation based on it. Added Github Action to run tests.

* Review fixes

.github/workflows/ci.yml

@@ -0,0 +1,34 @@
+name: Continuous Integration
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  test:
+    name: Test
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+        node-version: ["18", "20", "22"]
+
+    steps:
+      - name: Checkout project
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          check-latest: true
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test