Support forced snapshot overwrite

README.md

@@ -61,6 +61,13 @@ SBT settings:
   stay sane.
 
 - `snapshotsPackageName` - package name to use for generated file
+- `snapshotsForceOverwrite` - if set to `true`, snapshot assertions won't fail the tests,
+   but instead they will directly overwrite snapshot contents with the new value.
+
+   It is particularly useful in a setting where you want to only check snapshots on CI,
+   but always update them locally without having to explicitly accept.
+
+   Recommended configuration is therefore `snapshotsForceOverwrite := !sys.env.contains("CI")` - or whatever way you can detect that your code is running in CI
 
 [Sample MUnit tests](modules/example/src/test/scala/MunitExampleTests.scala)
 

modules/snapshots-buildtime/src/main/resources/MunitSnapshotsIntegration.scala

@@ -28,18 +28,17 @@ trait MunitSnapshotsIntegration {
   def assertSnapshot(name: String, contents: String) = {
     Snapshots.read(name) match {
       case None =>
-        Snapshots.recordChanges(
-          name,
-          contents,
-          Diffs.create(contents, "").createDiffOnlyReport()
-        )
+        // If snapshot is not found, we directly write its contents
+        Snapshots.write(name, contents)
 
       case Some(value) =>
         val diff = Diffs.create(contents, value)
         if (!diff.isEmpty) {
-          val diffReport = diff.createDiffOnlyReport()
-          Snapshots.recordChanges(name, contents, diffReport)
-          Assertions.assertNoDiff(contents, value)
+          if (!Snapshots.forceOverwrite) {
+            val diffReport = diff.createDiffOnlyReport()
+            Snapshots.recordChanges(name, contents, diffReport)
+            Assertions.assertNoDiff(contents, value)
+          } else Snapshots.write(name, contents)
         } else
           Snapshots.clearChanges(name)
     }

modules/snapshots-buildtime/src/main/scala/SnapshotsBuild.scala

@@ -148,7 +148,8 @@ object SnapshotsBuild {
       packageName: String,
       snapshotsDestination: File,
       sourceDestination: File,
-      tmpLocation: File
+      tmpLocation: File,
+      forceOverwrite: Boolean = true
   ) = {
     Files.createDirectories(sourceDestination.getParentFile().toPath)
 
@@ -157,7 +158,8 @@ object SnapshotsBuild {
       SnapshotsGenerate(
         snapshotsDestination,
         tmpLocation,
-        packageName
+        packageName,
+        forceOverwrite
       ).linesIterator.toList
     )
 
@@ -195,11 +197,12 @@ object SnapshotsBuild {
   private def SnapshotsGenerate(
       path: File,
       tempPath: File,
-      packageName: String
+      packageName: String,
+      forceOverwrite: Boolean
   ) =
     s"""
      |package $packageName
-     |object Snapshots extends com.indoorvivants.snapshots.Snapshots(location = "$path", tmpLocation = "$tempPath")
+     |object Snapshots extends com.indoorvivants.snapshots.Snapshots(location = "$path", tmpLocation = "$tempPath", forceOverwrite = $forceOverwrite)
       """.trim.stripMargin
 
 }

modules/snapshots-runtime/src/main/scala/Snapshots.scala

@@ -16,7 +16,11 @@
 
 package com.indoorvivants.snapshots
 
-case class Snapshots(location: String, tmpLocation: String) extends Platform {
+case class Snapshots(
+    location: String,
+    tmpLocation: String,
+    forceOverwrite: Boolean
+) extends Platform {
 
   private def getTmpFile(name: String) =
     tmpLocation.resolve(name)
@@ -36,6 +40,12 @@ case class Snapshots(location: String, tmpLocation: String) extends Platform {
     tmpFileDiff.fileWriteContents(diff)
   }
 
+  def write(name: String, contents: String): Unit = {
+    val file = location.resolve(name)
+    location.createDirectories()
+    file.fileWriteContents(contents)
+  }
+
   def clearChanges(name: String): Unit = {
     val tmpName     = name + "__snap.new"
     val tmpDiff     = name + "__snap.new.diff"

modules/snapshots-sbt-plugin/src/main/scala/SnapshotsPlugin.scala

@@ -43,6 +43,12 @@ object SnapshotsPlugin extends AutoPlugin {
       "Whether to add snapshot runtime to the build - true by default, you shouldn't need to touch this"
     )
 
+    val snapshotsForceOverwrite = settingKey[Boolean](
+      "(default: false) If set to true, tests where there is a snapshot mismatch won't fail, instead overwriting snapshot directly with new contents - meaning you don't have to run snapshotCheck/snapshotsAcceptAll.\n" +
+        "A recommended workflow with this option is to only enable it if NOT running on CI - e.g. `snapshotsForceOverwrite := !sys.env.contains(\"CI\")`.\n" +
+        "This way snapshot compliance will be checked on CI, but local workflow will be much quicker with immediate snapshot overwriting"
+    )
+
     val snapshotsTemporaryDirectory =
       settingKey[File]("Temp folder where snapshot diffs will be created")
 
@@ -82,7 +88,10 @@ object SnapshotsPlugin extends AutoPlugin {
       snapshotsProjectIdentifier    := thisProject.value.id,
       snapshotsAddRuntimeDependency := true,
       snapshotsIntegrations         := Seq.empty,
-      snapshotsTemporaryDirectory := (Test / managedResourceDirectories).value.head / "snapshots-tmp",
+      snapshotsForceOverwrite       := false,
+      snapshotsTemporaryDirectory := (
+        Test / managedResourceDirectories
+      ).value.head / "snapshots-tmp",
       snapshotsCheck := Def
         .task {
           SnapshotsBuild.checkSnapshots(
@@ -122,7 +131,8 @@ object SnapshotsPlugin extends AutoPlugin {
           snapshotsDestination =
             (Test / resourceDirectory).value / "snapshots" / snapshotsProjectIdentifier.value,
           sourceDestination = dest / "Snapshots.scala",
-          tmpLocation = snapshotsTemporaryDirectory.value
+          tmpLocation = snapshotsTemporaryDirectory.value,
+          forceOverwrite = snapshotsForceOverwrite.value
         )
 
         val integrations = snapshotsIntegrations.value.flatMap { integ =>

modules/snapshots-sbt-plugin/src/sbt-test/basic/force-overwrite/build.sbt

@@ -0,0 +1,29 @@
+lazy val root = projectMatrix
+  .in(file("."))
+  .jvmPlatform(Seq("3.3.1", "2.13.12"))
+  .nativePlatform(Seq("3.3.1"))
+  .jsPlatform(Seq("3.3.1"))
+  .settings(
+    snapshotsPackageName := "example.bla",
+    snapshotsIntegrations += SnapshotIntegration.MUnit,
+    libraryDependencies +=
+      "org.scalameta" %%% "munit" % "1.0.0-M7" % Test,
+    scalaJSLinkerConfig ~= (_.withModuleKind(ModuleKind.CommonJSModule)),
+    snapshotsForceOverwrite := true,
+    check := {
+      val dir =
+        (Test / resourceDirectory).value / "snapshots" / snapshotsProjectIdentifier.value
+
+      val contents = IO.read(dir / "my.snapshot")
+      val expected = "hello - more stuff"
+
+      assert(
+        contents == expected,
+        s"Snapshot contents didn't match: expected `$expected`, got `$contents`"
+      )
+
+    }
+  )
+  .enablePlugins(SnapshotsPlugin)
+
+val check = taskKey[Unit]("")

modules/snapshots-sbt-plugin/src/sbt-test/basic/force-overwrite/test

@@ -0,0 +1,9 @@
+$ exists src/test/resources/snapshots/root3/my.snapshot
+$ exists src/test/resources/snapshots/rootNative3/my.snapshot
+$ exists src/test/resources/snapshots/rootJS3/my.snapshot
+> root3/test
+> rootNative3/test
+> rootJS3/test
+> root3/check
+> rootNative3/check
+> rootJS3/check

modules/snapshots-sbt-plugin/src/sbt-test/basic/basic/build.sbt → modules/snapshots-sbt-plugin/src/sbt-test/basic/project-matrix/build.sbt

@@ -8,6 +8,7 @@ lazy val root = projectMatrix
     snapshotsIntegrations += SnapshotIntegration.MUnit,
     libraryDependencies +=
       "org.scalameta" %%% "munit" % "1.0.0-M7" % Test,
-    scalaJSLinkerConfig ~= (_.withModuleKind(ModuleKind.CommonJSModule))
+    scalaJSLinkerConfig ~= (_.withModuleKind(ModuleKind.CommonJSModule)),
   )
   .enablePlugins(SnapshotsPlugin)
+

modules/snapshots-sbt-plugin/src/sbt-test/basic/project-matrix/project/plugins.sbt

@@ -0,0 +1,6 @@
+addSbtPlugin(
+  "com.indoorvivants.snapshots" % "sbt-snapshots" % sys.props("plugin.version")
+)
+addSbtPlugin("org.scala-native" % "sbt-scala-native"  % "0.4.17")
+addSbtPlugin("com.eed3si9n"     % "sbt-projectmatrix" % "0.9.1")
+addSbtPlugin("org.scala-js"     % "sbt-scalajs"       % "1.14.0")

modules/snapshots-sbt-plugin/src/sbt-test/basic/project-matrix/src/test/scala/Tests.scala

@@ -0,0 +1,10 @@
+package example.bla
+
+import com.indoorvivants.snapshots.munit_integration._
+import munit._
+
+class MunitExampleTests extends FunSuite with MunitSnapshotsIntegration {
+  test("hello") {
+    assertSnapshot("my.snapshot", "hello - more stuff")
+  }
+}