Ignore file excluded from git

Git has a .gitignore which can be used to exclude files
from getting into the repository. It's pointless to scan
files ignored via this mechanism as we'll fail to stage
any changes to them.

This approach reads one .gitignore are the top of the file
and then use it to check all the paths. This is not _exact_
but I think it's good enough.

I say that this is not exact because Git supports .gitignore
file nested at arbitrary depth in the repository. To implement
that, we'd need to re-implement the `walk` function which is
not worth it in the scope of this issue.

Author: daddykotex

build.sbt

@@ -121,6 +121,7 @@ lazy val core = myCrossProject("core")
       Dependencies.decline,
       Dependencies.fs2Core,
       Dependencies.fs2Io,
+      Dependencies.gitignore,
       Dependencies.http4sCirce,
       Dependencies.http4sClient,
       Dependencies.http4sCore,

modules/core/src/main/scala/org/scalasteward/core/edit/update/ScannerAlg.scala

@@ -18,6 +18,8 @@ package org.scalasteward.core.edit.update
 
 import better.files.File
 import cats.effect.Concurrent
+import cats.syntax.functor._
+import com.github.arturopala.gitignore.GitIgnore
 import fs2.Stream
 import org.scalasteward.core.data.{Dependency, Repo, Version}
 import org.scalasteward.core.edit.update.data.{ModulePosition, VersionPosition}
@@ -56,19 +58,35 @@ final class ScannerAlg[F[_]](implicit
       .compile
       .foldMonoid
 
+  private def getGitIgnore(repoDir: File): F[Option[GitIgnore]] = {
+    val gitIgnore = repoDir / ".gitignore"
+    fileAlg.readFile(gitIgnore).map(_.map(GitIgnore.parse))
+  }
+
   private def findPathsContaining(
       repo: Repo,
       config: RepoConfig,
       string: String
-  ): Stream[F, FileData] =
-    Stream.eval(workspaceAlg.repoDir(repo)).flatMap { repoDir =>
-      val fileFilter = (file: File) => {
-        val path = repoDir.relativize(file).toString
-        val cond = !path.startsWith(".git/") &&
-          config.updates.fileExtensionsOrDefault.exists(path.endsWith)
-        Option.when(cond)(path)
-      }
-      val contentFilter = (content: String) => Some(content).filter(_.contains(string))
-      fileAlg.findFiles(repoDir, fileFilter, contentFilter).map(FileData.tupled)
+  ): Stream[F, FileData] = {
+    def fileFilter(repoDir: File, maybeGitIgnore: Option[GitIgnore]) = (file: File) => {
+      val path = repoDir.relativize(file).toString
+      val notDotGit = !path.startsWith(".git/")
+      val onlyKeepConfiguredExtensions =
+        config.updates.fileExtensionsOrDefault.exists(path.endsWith)
+      val allowedByGitIgnore = maybeGitIgnore.map(_.isAllowed(path)).getOrElse(true)
+      val cond = notDotGit &&
+        onlyKeepConfiguredExtensions &&
+        allowedByGitIgnore
+      Option.when(cond)(path)
     }
+    val contentFilter = (content: String) => Some(content).filter(_.contains(string))
+
+    for {
+      repoDir <- Stream.eval(workspaceAlg.repoDir(repo))
+      maybeRootGitIgnore <- Stream.eval(getGitIgnore(repoDir))
+      files <- fileAlg
+        .findFiles(repoDir, fileFilter(repoDir, maybeRootGitIgnore), contentFilter)
+        .map(FileData.tupled)
+    } yield files
+  }
 }

modules/core/src/test/scala/org/scalasteward/core/edit/EditAlgTest.scala

@@ -27,21 +27,26 @@ class EditAlgTest extends FunSuite {
     val update = ("org.typelevel".g % "cats-core".a % "1.2.0" %> "1.3.0").single
     val file1 = repoDir / "build.sbt"
     val file2 = repoDir / "project/Dependencies.scala"
+    val gitignore = repoDir / ".gitignore"
 
     val state = MockState.empty
-      .addFiles(file1 -> """val catsVersion = "1.2.0"""", file2 -> "")
+      .addFiles(file1 -> """val catsVersion = "1.2.0"""", file2 -> "", gitignore -> "")
       .flatMap(editAlg.applyUpdate(data, update).runS)
       .unsafeRunSync()
 
     val expected = MockState.empty.copy(
       trace = Vector(
+        Cmd("read", gitignore.pathAsString),
         Cmd("test", "-f", repoDir.pathAsString),
+        Cmd("test", "-f", gitignore.pathAsString),
         Cmd("test", "-f", file1.pathAsString),
         Cmd("read", file1.pathAsString),
         Cmd("test", "-f", (repoDir / "project").pathAsString),
         Cmd("test", "-f", file2.pathAsString),
         Cmd("read", file2.pathAsString),
+        Cmd("read", gitignore.pathAsString),
         Cmd("test", "-f", repoDir.pathAsString),
+        Cmd("test", "-f", gitignore.pathAsString),
         Cmd("test", "-f", file1.pathAsString),
         Cmd("read", file1.pathAsString),
         Cmd("test", "-f", (repoDir / "project").pathAsString),
@@ -51,7 +56,7 @@ class EditAlgTest extends FunSuite {
         Cmd("write", file1.pathAsString),
         Cmd(gitStatus(repoDir))
       ),
-      files = Map(file1 -> """val catsVersion = "1.3.0"""", file2 -> "")
+      files = Map(file1 -> """val catsVersion = "1.3.0"""", file2 -> "", gitignore -> "")
     )
 
     assertEquals(state, expected)
@@ -65,6 +70,7 @@ class EditAlgTest extends FunSuite {
     val data = RepoData(repo, cache, RepoConfig.empty)
     val repoDir = workspaceAlg.repoDir(repo).unsafeRunSync()
     val update = ("org.scalameta".g % "scalafmt-core".a % "2.0.0" %> "2.1.0").single
+    val gitignore = repoDir / ".gitignore"
     val scalafmtConf = repoDir / scalafmtConfName
     val scalafmtConfContent = """maxColumn = 100
                                 |version = 2.0.0
@@ -73,18 +79,22 @@ class EditAlgTest extends FunSuite {
     val buildSbt = repoDir / "build.sbt"
 
     val state = MockState.empty
-      .addFiles(scalafmtConf -> scalafmtConfContent, buildSbt -> "")
+      .addFiles(scalafmtConf -> scalafmtConfContent, buildSbt -> "", gitignore -> "")
       .flatMap(editAlg.applyUpdate(data, update).runS)
       .unsafeRunSync()
 
     val expected = MockState.empty.copy(
       trace = Vector(
+        Cmd("read", gitignore.pathAsString),
         Cmd("test", "-f", repoDir.pathAsString),
+        Cmd("test", "-f", gitignore.pathAsString),
         Cmd("test", "-f", scalafmtConf.pathAsString),
         Cmd("read", scalafmtConf.pathAsString),
         Cmd("test", "-f", buildSbt.pathAsString),
         Cmd("read", buildSbt.pathAsString),
+        Cmd("read", gitignore.pathAsString),
         Cmd("test", "-f", repoDir.pathAsString),
+        Cmd("test", "-f", gitignore.pathAsString),
         Cmd("test", "-f", scalafmtConf.pathAsString),
         Cmd("read", scalafmtConf.pathAsString),
         Cmd("test", "-f", buildSbt.pathAsString),
@@ -109,7 +119,8 @@ class EditAlgTest extends FunSuite {
             |version = 2.1.0
             |align.openParenCallSite = false
             |""".stripMargin,
-        buildSbt -> ""
+        buildSbt -> "",
+        gitignore -> ""
       )
     )
 

project/Dependencies.scala

@@ -20,6 +20,7 @@ object Dependencies {
   val disciplineMunit = "org.typelevel" %% "discipline-munit" % "1.0.9"
   val fs2Core = "co.fs2" %% "fs2-core" % "3.6.1"
   val fs2Io = "co.fs2" %% "fs2-io" % fs2Core.revision
+  val gitignore = "com.github.arturopala" %% "gitignore" % "0.4.0"
   val http4sCore = "org.http4s" %% "http4s-core" % "1.0.0-M39"
   val http4sCirce = "org.http4s" %% "http4s-circe" % http4sCore.revision
   val http4sClient = "org.http4s" %% "http4s-client" % http4sCore.revision