feat(test): Unit testing using kurtestosis (#161)

**Description**

[`kurtestosis`](https://github.com/ethereum-optimism/kurtestosis),
currently an MVP, is a unit test runner for `starlark`/`kurtosis`. It
allows for lower-level testing that would otherwise require costly and
complex environment setup and introduce unjustifiable test code
complexity.

This PR adds a PoC test for a simple piece of functionality,
`label_from_image` function in `util.star`. The test is then executed as
a part of the PR pipeline. `mise` is introduced to manage dependencies.

.github/workflows/per-pr.yml

@@ -46,3 +46,15 @@ jobs:
       - name: Kurtosis Lint
         run: kurtosis lint ${{ github.workspace }}
 
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+
+      - name: Install mise
+        uses: jdx/mise-action@v2
+
+      - name: Run kurtestosis tests
+        run: kurtestosis .
+

README.md

@@ -663,10 +663,43 @@ kurtosis service stop <enclave-name> <service-name>
 kurtosis service start <enclave-name> <service-name>
 ```
 
+## Development
+
+### Development environment
+
+We use [`mise`](https://mise.jdx.dev/) as a dependency manager for these tools.
+Once properly installed, `mise` will provide the correct versions for each tool. `mise` does not
+replace any other installations of these binaries and will only serve these binaries when you are
+working inside of the `optimism-package` directory.
+
+#### Install `mise`
+
+Install `mise` by following the instructions provided on the
+[Getting Started page](https://mise.jdx.dev/getting-started.html#_1-install-mise-cli).
+
+#### Install dependencies
+
+```sh
+mise install
+```
+
 ## Contributing
 
 If you have made changes and would like to submit a PR, test locally and make sure to run `lint` on your changes
 
 ```bash
 kurtosis lint --format .
 ```
+
+### Testing
+
+#### Unit tests
+
+We are using [`kurtestosis`](https://github.com/ethereum-optimism/kurtestosis) to run a set of unit tests against the starlark code:
+
+```bash
+# To run all unit tests
+kurtestosis .
+```
+
+The tests can be found in `*_test.star` scripts located in the `test` directory.

mise.toml

@@ -0,0 +1,4 @@
+[tools]
+
+# Core dependencies
+"ubi:ethereum-optimism/kurtestosis" = "0.0.5"

test/util_test.star

@@ -0,0 +1,60 @@
+util = import_module("/src/util.star")
+
+
+def test_label_from_image_short_image_name(plan):
+    image_name = "my-image"
+    image_label = util.label_from_image(image_name)
+
+    expect.eq(image_name, image_label)
+
+
+def test_label_from_image_63_character_image_name(plan):
+    image_name = ("tenletters" * 6) + "333"
+    expect.eq(len(image_name), 63)
+
+    image_label = util.label_from_image(image_name)
+    expect.eq(len(image_label), 63)
+    expect.eq(image_name, image_label)
+
+
+def test_label_from_image_64_character_image_name_no_slashes(plan):
+    image_name = ("tenletters" * 6) + "4444"
+    expect.eq(len(image_name), 64)
+
+    image_label = util.label_from_image(image_name)
+    expect.eq(len(image_label), 63)
+    expect.eq(image_name[-63:], image_label)
+
+
+def test_label_from_image_long_image_name_no_slashes(plan):
+    image_name = "tenletters" * 10
+    expect.eq(len(image_name), 100)
+
+    image_label = util.label_from_image(image_name)
+    expect.eq(len(image_label), 63)
+    expect.eq(image_name[-63:], image_label)
+
+
+def test_label_from_image_long_image_name_one_slash(plan):
+    image_suffix = "444"
+    image_name = "/".join(["tenletters" * 6, image_suffix])
+
+    image_label = util.label_from_image(image_name)
+    expect.eq(image_suffix, image_label)
+
+
+def test_label_from_image_long_image_name_more_slashes(plan):
+    image_suffix = "/".join(["slash", "slash2", "slash3"])
+    image_name = "/".join(["tenletters" * 8, image_suffix])
+
+    image_label = util.label_from_image(image_name)
+    expect.eq(image_suffix, image_label)
+
+
+def test_label_from_image_long_image_name_long_suffix(plan):
+    image_suffix = "/".join(["slash", "slash2", "slash3", "what-a-suffix" * 5])
+    image_name = "/".join(["tenletters" * 8, image_suffix])
+
+    image_label = util.label_from_image(image_name)
+    expect.eq(len(image_label), 63)
+    expect.eq(image_suffix[-63:], image_label)