diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 50a3b0c..a26814e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -41,9 +41,10 @@ jobs:
       - name: Lint
         id: npm-lint
         run: npm run lint
-      # - name: Test
-      #   id: npm-ci-test
-      #   run: npm run ci-test
+
+      - name: Test
+        id: npm-ci-test
+        run: npm run ci-test
 
   test-attest-provenance:
     name: Test attest-provenance action
diff --git a/__tests__/__snapshots__/main.test.ts.snap b/__tests__/__snapshots__/main.test.ts.snap
new file mode 100644
index 0000000..7b0e3a8
--- /dev/null
+++ b/__tests__/__snapshots__/main.test.ts.snap
@@ -0,0 +1,39 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`main successfully run main 1`] = `
+{
+  "buildDefinition": {
+    "buildType": "https://slsa-framework.github.io/github-actions-buildtypes/workflow/v1",
+    "externalParameters": {
+      "workflow": {
+        "path": ".github/workflows/main.yml",
+        "ref": "main",
+        "repository": "https://github.com/owner/repo",
+      },
+    },
+    "internalParameters": {
+      "github": {
+        "event_name": "push",
+        "repository_id": "repo-id",
+        "repository_owner_id": "owner-id",
+      },
+    },
+    "resolvedDependencies": [
+      {
+        "digest": {
+          "gitCommit": "babca52ab0c93ae16539e5923cb0d7403b9a093b",
+        },
+        "uri": "git+https://github.com/owner/repo@refs/heads/main",
+      },
+    ],
+  },
+  "runDetails": {
+    "builder": {
+      "id": "https://github.com/actions/runner/github-hosted",
+    },
+    "metadata": {
+      "invocationId": "https://github.com/owner/repo/actions/runs/run-id/attempts/run-attempt",
+    },
+  },
+}
+`;
diff --git a/__tests__/index.test.ts b/__tests__/index.test.ts
new file mode 100644
index 0000000..34a4dfe
--- /dev/null
+++ b/__tests__/index.test.ts
@@ -0,0 +1,17 @@
+/**
+ * Unit tests for the action's entrypoint, src/index.ts
+ */
+
+import * as main from '../src/main'
+
+// Mock the action's entrypoint
+const runMock = jest.spyOn(main, 'run').mockImplementation()
+
+describe('index', () => {
+  it('calls run when imported', async () => {
+    // eslint-disable-next-line @typescript-eslint/no-require-imports
+    require('../src/index')
+
+    expect(runMock).toHaveBeenCalled()
+  })
+})
diff --git a/__tests__/main.test.ts b/__tests__/main.test.ts
new file mode 100644
index 0000000..a19e3e4
--- /dev/null
+++ b/__tests__/main.test.ts
@@ -0,0 +1,60 @@
+import * as core from '@actions/core'
+import * as main from '../src/main'
+
+// Mock the GitHub Actions core library
+jest.mock('@actions/core')
+const setOutputMock = jest.spyOn(core, 'setOutput')
+const setFailedMock = jest.spyOn(core, 'setFailed')
+
+// Ensure that setFailed doesn't set an exit code during tests
+setFailedMock.mockImplementation(() => {})
+
+describe('main', () => {
+  let outputs = {} as Record<string, string>
+
+  beforeEach(() => {
+    jest.resetAllMocks()
+    setOutputMock.mockImplementation((key, value) => {
+      outputs[key] = value
+    })
+  })
+
+  afterEach(() => {
+    outputs = {}
+  })
+
+  it('successfully run main', async () => {
+    const originalEnv = process.env
+    process.env = {
+      ...originalEnv,
+      GITHUB_REPOSITORY: 'owner/repo',
+      GITHUB_REF: 'refs/heads/main',
+      GITHUB_SHA: 'babca52ab0c93ae16539e5923cb0d7403b9a093b',
+      GITHUB_WORKFLOW_REF: 'owner/repo/.github/workflows/main.yml@main',
+      GITHUB_SERVER_URL: 'https://github.com',
+      GITHUB_EVENT_NAME: 'push',
+      GITHUB_REPOSITORY_ID: 'repo-id',
+      GITHUB_REPOSITORY_OWNER_ID: 'owner-id',
+      GITHUB_RUN_ID: 'run-id',
+      GITHUB_RUN_ATTEMPT: 'run-attempt',
+      RUNNER_ENVIRONMENT: 'github-hosted'
+    }
+
+    // Run the main function
+    await main.run()
+
+    // Verify that outputs were set correctly
+    expect(setOutputMock).toHaveBeenCalledTimes(2)
+
+    // Use the expected object in the test assertion
+    expect(outputs['predicate']).toMatchSnapshot()
+
+    expect(setOutputMock).toHaveBeenNthCalledWith(
+      2,
+      'predicate-type',
+      'https://slsa.dev/provenance/v1'
+    )
+
+    process.env = originalEnv
+  })
+})
diff --git a/jest.setup.js b/jest.setup.js
new file mode 100644
index 0000000..a535bd6
--- /dev/null
+++ b/jest.setup.js
@@ -0,0 +1 @@
+process.stdout.write = jest.fn()
diff --git a/package.json b/package.json
index 1d74d7d..3cecf36 100644
--- a/package.json
+++ b/package.json
@@ -46,6 +46,9 @@
       "js",
       "ts"
     ],
+    "setupFilesAfterEnv": [
+      "./jest.setup.js"
+    ],
     "testMatch": [
       "**/*.test.ts"
     ],