diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index a588d6d0c..4b57fbec4 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -1,22 +1,52 @@
 name: CI
-on: push
+on: [push, pull_request]
 
 jobs:
   build:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        node: ['16.x']
-    name: Node ${{ matrix.node }} sample
     steps:
-      - uses: actions/checkout@v2
-      - name: Setup node
-        uses: actions/setup-node@v2
+      - name: Git checkout
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
         with:
-          node-version: ${{ matrix.node }}
+          fetch-depth: 0
+
+      - name: Setup Node.js
+        uses: actions/setup-node@1a4442cacd436585916779262731d5b162bc6ec7
+        with:
+          node-version: 16
 
       - name: Install Dependencies
         run: yarn
 
       - name: Run Eslint checks
+        if: github.event_name == 'push'
         run: yarn check:es
+
+      - name: Run Changed tests only
+        if: github.event_name == 'pull_request'
+        timeout-minutes: 15
+        env:
+          TENDERLY_ACCOUNT_ID: ${{ secrets.TENDERLY_USERNAME }}
+          TENDERLY_PROJECT: ${{ secrets.TENDERLY_PROJECT }}
+          TENDERLY_TOKEN: ${{ secrets.TENDERLY_TOKEN }}
+          HTTP_PROVIDER_1: ${{ secrets.HTTP_PROVIDER_1 }}
+          HTTP_PROVIDER_10: ${{ secrets.HTTP_PROVIDER_10 }}
+          HTTP_PROVIDER_56: ${{ secrets.HTTP_PROVIDER_56 }}
+          HTTP_PROVIDER_137: ${{ secrets.HTTP_PROVIDER_137 }}
+          HTTP_PROVIDER_250: ${{ secrets.HTTP_PROVIDER_250 }}
+          HTTP_PROVIDER_1101: ${{ secrets.HTTP_PROVIDER_1101 }}
+          HTTP_PROVIDER_8453: ${{ secrets.HTTP_PROVIDER_8453 }}
+          HTTP_PROVIDER_42161: ${{ secrets.HTTP_PROVIDER_42161 }}
+          HTTP_PROVIDER_43114: ${{ secrets.HTTP_PROVIDER_43114 }}
+        run: |
+          CHANGED_TESTS=$(git diff --name-only origin/${{ github.base_ref }} origin/${{ github.head_ref }} | grep test.ts || true)
+          echo "$CHANGED_TESTS"
+          if [ -n "$CHANGED_TESTS" ]; then
+            echo "Running the following changed specs"
+            npx jest --ci --forceExit --verbose $CHANGED_TESTS
+          else
+            echo "There are no changed tests...skipping"
+          fi
+
+          printf '%s\n' "$TENDERLY_PROJECT" > test.txt
+          cat test.txt
diff --git a/src/dex/balancer-v2/new.test.ts b/src/dex/balancer-v2/new.test.ts
new file mode 100644
index 000000000..a10047991
--- /dev/null
+++ b/src/dex/balancer-v2/new.test.ts
@@ -0,0 +1,10 @@
+import dotenv from 'dotenv';
+dotenv.config();
+
+
+describe('Test', () => {
+  it('should pass', () => {
+    console.log(process.env.TENDERLY_PROJECT);
+    expect(true).toBe(true);
+  })
+});
diff --git a/test.txt b/test.txt
new file mode 100644
index 000000000..573541ac9
--- /dev/null
+++ b/test.txt
@@ -0,0 +1 @@
+0
diff --git a/tests/tenderly-simulation.ts b/tests/tenderly-simulation.ts
index ddc53c786..b1bcd5982 100644
--- a/tests/tenderly-simulation.ts
+++ b/tests/tenderly-simulation.ts
@@ -76,6 +76,7 @@ export class TenderlySimulation implements TransactionSimulator {
     }
 
     try {
+      await process.nextTick(() => { }); // https://stackoverflow.com/questions/69169492/async-external-function-leaves-open-handles-jest-supertest-express
       let res = await axios.post(
         `https://api.tenderly.co/api/v1/account/${TENDERLY_ACCOUNT_ID}/project/${TENDERLY_PROJECT}/fork`,
         {
@@ -109,6 +110,7 @@ export class TenderlySimulation implements TransactionSimulator {
     };
     try {
       if (stateOverrides) {
+        await process.nextTick(() => { }); // https://stackoverflow.com/questions/69169492/async-external-function-leaves-open-handles-jest-supertest-express
         const result = await axios.post(
           `
         https://api.tenderly.co/api/v1/account/${TENDERLY_ACCOUNT_ID}/project/${TENDERLY_PROJECT}/contracts/encode-states`,
@@ -133,6 +135,7 @@ export class TenderlySimulation implements TransactionSimulator {
         );
       }
 
+      await process.nextTick(() => { }); // https://stackoverflow.com/questions/69169492/async-external-function-leaves-open-handles-jest-supertest-express
       const { data } = await axios.post(
         `https://api.tenderly.co/api/v1/account/${TENDERLY_ACCOUNT_ID}/project/${TENDERLY_PROJECT}/fork/${this.forkId}/simulate`,
         _params,