From bbd88e04dcdb91e23c76c20b01bca41eaed6b06e Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Fri, 26 Jul 2019 09:51:30 -0700
Subject: [PATCH] Add scripted test for symlink source monitoring

The swoval library automatically watches the _target_ of symlinks. I had
been meaning to add a scripted test to ensure that in sbt continuous
builds detect changes to the target of symlinks. The naive approach of
just watching all of the files in the source directory doesn't work
because the native watch process will just watch the symlink node itself
and not detect updates to its target. This test would have thus failed
with 1.2.8.

Watching symlinked files doesn't work at the moment on windows, but does
work on mac and linux. Eventually I'd like there to be feature parity,
but, for now, we'll just skip the file target test on windows. At least
this test makes it explicit what does and doesn't work on each platform.
---
 sbt/src/sbt-test/watch/symlinks/build.sbt     | 46 +++++++++++++++++++
 .../symlinks/changes/file-source/Foo.scala    |  1 +
 .../watch/symlinks/changes/sources/Bar.scala  |  3 ++
 .../watch/symlinks/file-source/Foo.scala      |  1 +
 sbt/src/sbt-test/watch/symlinks/test          | 15 ++++++
 5 files changed, 66 insertions(+)
 create mode 100644 sbt/src/sbt-test/watch/symlinks/build.sbt
 create mode 100644 sbt/src/sbt-test/watch/symlinks/changes/file-source/Foo.scala
 create mode 100644 sbt/src/sbt-test/watch/symlinks/changes/sources/Bar.scala
 create mode 100644 sbt/src/sbt-test/watch/symlinks/file-source/Foo.scala
 create mode 100644 sbt/src/sbt-test/watch/symlinks/test

diff --git a/sbt/src/sbt-test/watch/symlinks/build.sbt b/sbt/src/sbt-test/watch/symlinks/build.sbt
new file mode 100644
index 000000000..09e1b7ad3
--- /dev/null
+++ b/sbt/src/sbt-test/watch/symlinks/build.sbt
@@ -0,0 +1,46 @@
+import java.nio.file.{ Files, Paths }
+import java.nio.file.StandardCopyOption.REPLACE_EXISTING
+
+val createSymlinks = taskKey[Unit]("create symlinks to source files and directories")
+createSymlinks := {
+  val base = baseDirectory.value.toPath
+  val srcDir = base / "src" / "main" / "scala"
+  val foo = Files.createDirectories(srcDir / "file-source") / "Foo.scala"
+  Files.createSymbolicLink(srcDir / "sources", Files.createDirectories(base / "sources"))
+  Files.deleteIfExists(foo)
+  Files.createSymbolicLink(foo, base / "file-source" / "Foo.scala")
+}
+
+ThisBuild / watchOnFileInputEvent := {
+  val srcDir = baseDirectory.value.toPath / "src" / "main" / "scala"
+  (_: Int, event: Watch.Event) =>
+    event.path match {
+      case p if p == (srcDir / "file-source" / "Foo.scala") => Watch.CancelWatch
+      case p if p == (srcDir / "sources" / "Bar.scala")     => Watch.CancelWatch
+      case _                                                => Watch.Ignore
+    }
+}
+
+val copySource = inputKey[Unit]("copy a source file from changes")
+copySource := {
+  val relative = Def.spaceDelimited("").parsed.head.split("/") match {
+    case Array(head)            => Paths.get(head)
+    case Array(head, tail @ _*) => tail.foldLeft(Paths.get(head))(_ / _)
+  }
+  val base = baseDirectory.value.toPath
+  Files.copy((base / "changes").resolve(relative), base.resolve(relative), REPLACE_EXISTING)
+}
+
+val removeLink = inputKey[Unit]("remove a symlink")
+removeLink := {
+  val relative = Def.spaceDelimited("").parsed.head.split("/") match {
+    case Array(head)            => Paths.get(head)
+    case Array(head, tail @ _*) => tail.foldLeft(Paths.get(head))(_ / _)
+  }
+  val srcDir = baseDirectory.value.toPath / "src" / "main" / "scala"
+  Files.deleteIfExists(srcDir.resolve(relative))
+}
+
+commands += Command.single("skipWindows") { (state, command) =>
+  if (scala.util.Properties.isWin) state else command :: state
+}
diff --git a/sbt/src/sbt-test/watch/symlinks/changes/file-source/Foo.scala b/sbt/src/sbt-test/watch/symlinks/changes/file-source/Foo.scala
new file mode 100644
index 000000000..f72abf33f
--- /dev/null
+++ b/sbt/src/sbt-test/watch/symlinks/changes/file-source/Foo.scala
@@ -0,0 +1 @@
+class Foo {}
\ No newline at end of file
diff --git a/sbt/src/sbt-test/watch/symlinks/changes/sources/Bar.scala b/sbt/src/sbt-test/watch/symlinks/changes/sources/Bar.scala
new file mode 100644
index 000000000..f124ae515
--- /dev/null
+++ b/sbt/src/sbt-test/watch/symlinks/changes/sources/Bar.scala
@@ -0,0 +1,3 @@
+package sources
+
+class Bar
\ No newline at end of file
diff --git a/sbt/src/sbt-test/watch/symlinks/file-source/Foo.scala b/sbt/src/sbt-test/watch/symlinks/file-source/Foo.scala
new file mode 100644
index 000000000..43c42f145
--- /dev/null
+++ b/sbt/src/sbt-test/watch/symlinks/file-source/Foo.scala
@@ -0,0 +1 @@
+class Foo
\ No newline at end of file
diff --git a/sbt/src/sbt-test/watch/symlinks/test b/sbt/src/sbt-test/watch/symlinks/test
new file mode 100644
index 000000000..70ab7d943
--- /dev/null
+++ b/sbt/src/sbt-test/watch/symlinks/test
@@ -0,0 +1,15 @@
+> createSymlinks
+
+> skipWindows ~compile; copySource file-source/Foo.scala
+
+> ~compile; copySource sources/Bar.scala
+
+> skipWindows ~compile; removeLink file-source/Foo.scala
+
+> ~compile; removeLink sources
+
+> ~compile; createSymlinks
+
+> copySource sources/Bar.scala
+
+> ~compile; removeLink sources/Bar.scala