Snapshot testing for MUnit. This project is a basic implementation of the snapshot tests.

After adding the munit-snapshot dependency:

libraryDependencies += "com.github.lolgab" %% "munit-snapshot" % "0.0.4" % Test

You can create a basic test in a file called ExampleSnapshotTest.scala:

package example

import munit.snapshot._
import upickle.default._

class ExampleSnapshotTest extends SnapshotSuite {
  snapshotTest("one plus one") {
    1 + 1
  }
}

Running the tests the first time will generate a file called ExampleSnapshotTest.json with the following content:

{
  "one plus one": 2
}

where "one plus one" is the test name (it should be unique in the file) and 2 is the result of the test evaluation.

The subsequent runs will evaluate the expression again, and fail when they do not match the saved json file.

If a test is removed, running the tests will remove the key from the json file.

Here you can see what happens if I change the json file to:

{
  "one plus one": 3
}

Running the test again will output:

6:class ExampleSnapshotTest extends SnapshotSuite {
7:  snapshotTest("one plus one") {
8:    1 + 1
values are not the same
=> Obtained
2
=> Diff (- obtained, + expected)
-2
+3