diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..11a5634
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,79 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+  pull_request:
+  schedule:
+    - cron: "0 5 * * 1"
+
+permissions:
+  contents: read
+
+concurrency:
+  # yamllint disable-line rule:line-length
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: Build test configuration for esphome:${{ matrix.esphome-version }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        esphome-version:
+          - stable
+          - beta
+          - dev
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4.1.7
+      - name: Run action
+        uses: ./
+        id: esphome-build
+        with:
+          yaml_file: tests/test.yaml
+          version: ${{ matrix.esphome-version }}
+          platform: linux/amd64
+          cache: true
+          release_summary: "Test release summary"
+          release_url: "https://github.com/esphome/build-action"
+      - name: Write version to file
+        run: echo ${{ steps.esphome-build.outputs.version }} > ${{ steps.esphome-build.outputs.name }}/version
+      - name: Upload ESPHome binary
+        uses: actions/upload-artifact@v4.3.3
+        with:
+          name: build-output-files-${{ matrix.esphome-version }}
+          path: ${{ steps.esphome-build.outputs.name }}
+
+  verify:
+    name: Verify output files for esphome:${{ matrix.esphome-version }}
+    runs-on: ubuntu-latest
+    needs: build
+    strategy:
+      fail-fast: false
+      matrix:
+        esphome-version:
+          - stable
+          - beta
+          - dev
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4.1.7
+      - name: Download files
+        uses: actions/download-artifact@v4.1.7
+        with:
+          name: build-output-files-${{ matrix.esphome-version }}
+
+      - name: List files
+        run: |-
+          ls -al
+          tree
+
+      - name: Validate json file matches manifest-template.json
+        run: |
+          jq -n --arg md5 "$(md5sum test-esp32.ota.bin | head -c 32)" -f tests/manifest-template.json > /tmp/manifest.json
+          diff <(jq --sort-keys . /tmp/manifest.json) <(jq --sort-keys . manifest.json)
diff --git a/.gitignore b/.gitignore
index 9594b4d..2c0f109 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +1,6 @@
-# Gitignore settings for ESPHome
-# This is an example and may include too much for your use-case.
-# You can modify this file to suit your needs.
-/.esphome/
-/secrets.yaml
+.esphome
 venv
 *.bin
 *.json
+!/tests/manifest-template.json
 config/
diff --git a/action.yml b/action.yml
index 7543829..601ea2e 100644
--- a/action.yml
+++ b/action.yml
@@ -89,14 +89,12 @@ runs:
         --workdir /github/workspace \
         -v "$(pwd)":"/github/workspace" -v "$HOME:$HOME" \
         --user $(id -u):$(id -g) \
-        -e INPUT_YAML_FILE -e HOME \
-        -e INPUT_RELEASE_SUMMARY -e INPUT_RELEASE_URL \
-        -e GITHUB_JOB -e GITHUB_REF -e GITHUB_SHA -e GITHUB_REPOSITORY \
-        -e GITHUB_REPOSITORY_OWNER -e GITHUB_RUN_ID -e GITHUB_RUN_NUMBER \
-        -e GITHUB_ACTOR -e GITHUB_OUTPUT \
-        -e GITHUB_ACTIONS=true -e CI=true \
+        -e HOME \
         esphome:${{ inputs.version }} \
-        ${{ inputs.yaml_file }}
+        ${{ inputs.yaml_file }} \
+        --release-summary "${{ inputs.release_summary }}" \
+        --release-url "${{ inputs.release_url }}" \
+        --outputs-file "$GITHUB_OUTPUT"
 
 branding:
   icon: "archive"
diff --git a/entrypoint.py b/entrypoint.py
index 90c6812..ccbe389 100755
--- a/entrypoint.py
+++ b/entrypoint.py
@@ -1,14 +1,17 @@
 #!/usr/bin/python3
+from __future__ import annotations
 
-import os
-import subprocess
-import sys
+import argparse
+from dataclasses import dataclass
+import hashlib
 import json
+import re
 import shutil
+import subprocess
+import sys
 from pathlib import Path
-import re
+
 import yaml
-import hashlib
 
 
 ESP32_CHIP_FAMILIES = {
@@ -19,152 +22,254 @@
     "ESP32C6": "ESP32-C6",
 }
 
-if len(sys.argv) != 2:
-    print("Usage: entrypoint.py <image_file>")
-    sys.exit(1)
-
-filename = Path(sys.argv[1])
-
-print("::group::Compile firmware")
-rc = subprocess.run(
-    ["esphome", "compile", filename],
-    stdout=sys.stdout,
-    stderr=sys.stderr,
-    check=False,
-)
-if rc.returncode != 0:
-    sys.exit(rc)
-
-print("::endgroup::")
-
-print("::group::Get ESPHome version")
-try:
-    version = subprocess.check_output(["esphome", "version"])
-except subprocess.CalledProcessError as e:
-    sys.exit(e.returncode)
-version = version.decode("utf-8")
-print(version)
-version = version.split(" ")[1]
-with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as github_output:
-    print(f"esphome-version={version}", file=github_output)
-print("::endgroup::")
-
-print("::group::Get config")
-try:
-    config = subprocess.check_output(["esphome", "config", filename], stderr=sys.stderr)
-except subprocess.CalledProcessError as e:
-    sys.exit(e.returncode)
-
-config = config.decode("utf-8")
-print(config)
-
-yaml.add_multi_constructor("", lambda _, t, n: t + " " + n.value)
-config = yaml.load(config, Loader=yaml.FullLoader)
-
-name = config["esphome"]["name"]
-
-with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as github_output:
-    print(f"original_name={name}", file=github_output)
-
-platform = ""
-if "esp32" in config:
-    platform = config["esp32"]["variant"].lower()
-elif "esp8266" in config:
-    platform = "esp8266"
-elif "rp2040" in config:
-    platform = "rp2040"
-
-name += f"-{platform}"
-
-with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as github_output:
-    print(f"name={name}", file=github_output)
-print("::endgroup::")
-
-file_base = Path(name)
-
-print("::group::Get IDEData")
-try:
-    idedata = subprocess.check_output(
-        ["esphome", "idedata", filename], stderr=sys.stderr
-    )
-except subprocess.CalledProcessError as e:
-    sys.exit(e.returncode)
-
-data = json.loads(idedata.decode("utf-8"))
-print(json.dumps(data, indent=2))
-
-elf = Path(data["prog_path"])
-if platform == "rp2040":
-    source_factory_bin = elf.with_name("firmware.uf2")
-    dest_factory_bin = file_base / f"{name}.uf2"
-else:
-    source_factory_bin = elf.with_name("firmware.factory.bin")
-    dest_factory_bin = file_base / f"{name}.factory.bin"
 
-source_ota_bin = elf.with_name("firmware.ota.bin")
-dest_ota_bin = file_base / f"{name}.ota.bin"
+def parse_args(argv):
+    """Parse the arguments."""
+    parser = argparse.ArgumentParser()
+    parser.add_argument("configuration", help="Path to the configuration file")
+    parser.add_argument("--release-summary", help="Release summary", nargs="?")
+    parser.add_argument("--release-url", help="Release URL", nargs="?")
 
-print("::endgroup::")
+    parser.add_argument("--outputs-file", help="GitHub Outputs file", nargs="?")
 
-print("::group::Copy firmware file(s) to folder")
-file_base.mkdir(parents=True, exist_ok=True)
+    return parser.parse_args(argv[1:])
 
-shutil.copyfile(source_factory_bin, dest_factory_bin)
-shutil.copyfile(source_ota_bin, dest_ota_bin)
 
-print("::endgroup::")
-
-
-print("::group::Write manifest.json file")
-
-
-chip_family = None
-define: str
-has_factory_part = False
-for define in data["defines"]:
-    if define == "USE_ESP8266":
-        chip_family = "ESP8266"
-        has_factory_part = True
-        break
-    if define == "USE_RP2040":
-        chip_family = "RP2040"
-        break
-    if m := re.match(r"USE_ESP32_VARIANT_(\w+)", define):
-        chip_family = m.group(1)
-        if chip_family not in ESP32_CHIP_FAMILIES:
-            raise Exception(f"Unsupported chip family: {chip_family}")
-
-        chip_family = ESP32_CHIP_FAMILIES[chip_family]
-        has_factory_part = True
-        break
-
-ota_md5 = hashlib.md5(open(dest_ota_bin, "rb").read()).hexdigest()
-
-manifest = {
-    "chipFamily": chip_family,
-    "ota": {
-        "path": str(dest_ota_bin),
-        "md5": ota_md5,
-    },
-}
-
-if release_summary := os.environ.get("INPUT_RELEASE_SUMMARY"):
-    manifest["ota"]["summary"] = release_summary
-if release_url := os.environ.get("INPUT_RELEASE_URL"):
-    manifest["ota"]["release_url"] = release_url
+def compile_firmware(filename: Path) -> int:
+    """Compile the firmware."""
+    print("::group::Compile firmware")
+    rc = subprocess.run(
+        ["esphome", "compile", filename],
+        stdout=sys.stdout,
+        stderr=sys.stderr,
+        check=False,
+    )
+    print("::endgroup::")
+    return rc.returncode
+
+
+def get_esphome_version(outputs_file: str | None) -> tuple[str, int]:
+    """Get the ESPHome version."""
+    print("::group::Get ESPHome version")
+    try:
+        version = subprocess.check_output(["esphome", "version"])
+    except subprocess.CalledProcessError as e:
+        print("::endgroup::")
+        return "", e.returncode
+
+    version = version.decode("utf-8")
+    print(version)
+    version = version.split(" ")[1].strip()
+    if outputs_file:
+        with open(outputs_file, "a", encoding="utf-8") as output:
+            print(f"esphome-version={version}", file=output)
+    print("::endgroup::")
+    return version, 0
+
+
+@dataclass
+class Config:
+    """Configuration data."""
+
+    name: str
+    platform: str
+    original_name: str
+
+    def dest_factory_bin(self, file_base: Path) -> Path:
+        """Get the destination factory binary path."""
+        if self.platform == "rp2040":
+            return file_base / f"{self.name}.uf2"
+        return file_base / f"{self.name}.factory.bin"
+
+    def dest_ota_bin(self, file_base: Path) -> Path:
+        """Get the destination OTA binary path."""
+        return file_base / f"{self.name}.ota.bin"
+
+    def source_factory_bin(self, elf: Path) -> Path:
+        """Get the source factory binary path."""
+        if self.platform == "rp2040":
+            return elf.with_name("firmware.uf2")
+        return elf.with_name("firmware.factory.bin")
+
+    def source_ota_bin(self, elf: Path) -> Path:
+        """Get the source OTA binary path."""
+        return elf.with_name("firmware.ota.bin")
+
+
+def get_config(filename: Path, outputs_file: str | None) -> tuple[Config | None, int]:
+    """Get the configuration."""
+    print("::group::Get config")
+    try:
+        config = subprocess.check_output(
+            ["esphome", "config", filename], stderr=sys.stderr
+        )
+    except subprocess.CalledProcessError as e:
+        return None, e.returncode
+
+    config = config.decode("utf-8")
+    print(config)
+
+    yaml.add_multi_constructor("", lambda _, t, n: t + " " + n.value)
+    config = yaml.load(config, Loader=yaml.FullLoader)
+
+    original_name = config["esphome"]["name"]
+
+    if outputs_file:
+        with open(outputs_file, "a", encoding="utf-8") as output:
+            print(f"original_name={original_name}", file=output)
+
+    platform = ""
+    if "esp32" in config:
+        platform = config["esp32"]["variant"].lower()
+    elif "esp8266" in config:
+        platform = "esp8266"
+    elif "rp2040" in config:
+        platform = "rp2040"
+
+    name = f"{original_name}-{platform}"
+
+    if outputs_file:
+        with open(outputs_file, "a", encoding="utf-8") as output:
+            print(f"name={name}", file=output)
+    print("::endgroup::")
+    return Config(name=name, platform=platform, original_name=original_name), 0
+
+
+def get_idedata(filename: Path) -> tuple[dict | None, int]:
+    """Get the IDEData."""
+    print("::group::Get IDEData")
+    try:
+        idedata = subprocess.check_output(
+            ["esphome", "idedata", filename], stderr=sys.stderr
+        )
+    except subprocess.CalledProcessError as e:
+        return None, e.returncode
+
+    data = json.loads(idedata.decode("utf-8"))
+    print(json.dumps(data, indent=2))
+    print("::endgroup::")
+    return data, 0
+
+
+def generate_manifest(
+    idedata: dict,
+    factory_bin: Path,
+    ota_bin: Path,
+    release_summary: str | None,
+    release_url: str | None,
+) -> tuple[dict | None, int]:
+    """Generate the manifest."""
+    print("::group::Generate manifest")
+
+    chip_family = None
+    define: str
+    has_factory_part = False
+    for define in idedata["defines"]:
+        if define == "USE_ESP8266":
+            chip_family = "ESP8266"
+            has_factory_part = True
+            break
+        if define == "USE_RP2040":
+            chip_family = "RP2040"
+            break
+        if m := re.match(r"USE_ESP32_VARIANT_(\w+)", define):
+            chip_family = m.group(1)
+            if chip_family not in ESP32_CHIP_FAMILIES:
+                print(f"ERROR: Unsupported chip family: {chip_family}")
+                return None, 1
+
+            chip_family = ESP32_CHIP_FAMILIES[chip_family]
+            has_factory_part = True
+            break
+
+    with open(ota_bin, "rb") as f:
+        ota_md5 = hashlib.md5(f.read()).hexdigest()
+
+    manifest = {
+        "chipFamily": chip_family,
+        "ota": {
+            "path": str(ota_bin),
+            "md5": ota_md5,
+        },
+    }
+
+    if release_summary:
+        manifest["ota"]["summary"] = release_summary
+    if release_url:
+        manifest["ota"]["release_url"] = release_url
+
+    if has_factory_part:
+        manifest["parts"] = [
+            {
+                "path": str(factory_bin),
+                "offset": 0x00,
+            }
+        ]
+
+    print("Writing manifest file:")
+    print(json.dumps(manifest, indent=2))
+
+    print("::endgroup::")
+    return manifest, 0
+
+
+def main(argv) -> int:
+    """Main entrypoint."""
+    args = parse_args(argv)
+
+    filename = Path(args.configuration)
+
+    if (rc := compile_firmware(filename)) != 0:
+        return rc
+
+    _, rc = get_esphome_version(args.outputs_file)
+    if rc != 0:
+        return rc
+
+    config, rc = get_config(filename, args.outputs_file)
+    if rc != 0:
+        return rc
+
+    assert config is not None
+
+    file_base = Path(config.name)
+
+    idedata, rc = get_idedata(filename)
+    if rc != 0:
+        return rc
+
+    print("::group::Copy firmware file(s) to folder")
+
+    elf = Path(idedata["prog_path"])
+
+    source_factory_bin = config.source_factory_bin(elf)
+    dest_factory_bin = config.dest_factory_bin(file_base)
+
+    source_ota_bin = config.source_ota_bin(elf)
+    dest_ota_bin = config.dest_ota_bin(file_base)
+
+    file_base.mkdir(parents=True, exist_ok=True)
+
+    shutil.copyfile(source_factory_bin, dest_factory_bin)
+    shutil.copyfile(source_ota_bin, dest_ota_bin)
+
+    print("::endgroup::")
+
+    manifest, rc = generate_manifest(
+        idedata,
+        dest_factory_bin,
+        dest_ota_bin,
+        args.release_summary,
+        args.release_url,
+    )
+    if rc != 0:
+        return rc
 
-if has_factory_part:
-    manifest["parts"] = [
-        {
-            "path": str(dest_factory_bin),
-            "offset": 0x00,
-        }
-    ]
+    with open(file_base / "manifest.json", "w", encoding="utf-8") as f:
+        json.dump(manifest, f, indent=2)
 
-print("Writing manifest file:")
-print(json.dumps(manifest, indent=2))
+    return 0
 
-with open(file_base / "manifest.json", "w", encoding="utf-8") as f:
-    json.dump(manifest, f, indent=2)
 
-print("::endgroup::")
+if __name__ == "__main__":
+    sys.exit(main(sys.argv))
diff --git a/tests/.gitignore b/tests/.gitignore
new file mode 100644
index 0000000..d8b4157
--- /dev/null
+++ b/tests/.gitignore
@@ -0,0 +1,5 @@
+# Gitignore settings for ESPHome
+# This is an example and may include too much for your use-case.
+# You can modify this file to suit your needs.
+/.esphome/
+/secrets.yaml
diff --git a/tests/manifest-template.json b/tests/manifest-template.json
new file mode 100644
index 0000000..e705442
--- /dev/null
+++ b/tests/manifest-template.json
@@ -0,0 +1,15 @@
+{
+  "chipFamily": "ESP32",
+  "ota": {
+    "path": "test-esp32/test-esp32.ota.bin",
+    "md5": "\($md5)",
+    "summary": "Test release summary",
+    "release_url": "https://github.com/esphome/build-action"
+  },
+  "parts": [
+    {
+      "path": "test-esp32/test-esp32.factory.bin",
+      "offset": 0
+    }
+  ]
+}
diff --git a/tests/test.yaml b/tests/test.yaml
new file mode 100644
index 0000000..cb9a6bb
--- /dev/null
+++ b/tests/test.yaml
@@ -0,0 +1,5 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev