From 69be8796847dc1fa42434ab4a111aeeb60a94c75 Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Sat, 24 Oct 2020 10:07:13 -0700
Subject: [PATCH] Reinstate watchBeforeCommand callback

A user reported that the watchBeforeCommand callback was not being
invoked in sbt 1.4.{0, 1}. This was an oversight that occurred when
refactoring watch for the thin client and there previously had been no
regression test for that callback.
---
 main/src/main/scala/sbt/internal/Continuous.scala | 5 ++++-
 sbt/src/sbt-test/watch/before-command/build.sbt   | 5 +++++
 sbt/src/sbt-test/watch/before-command/test        | 3 +++
 3 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 sbt/src/sbt-test/watch/before-command/build.sbt
 create mode 100644 sbt/src/sbt-test/watch/before-command/test

diff --git a/main/src/main/scala/sbt/internal/Continuous.scala b/main/src/main/scala/sbt/internal/Continuous.scala
index bd8c4de9e..1a6790c76 100644
--- a/main/src/main/scala/sbt/internal/Continuous.scala
+++ b/main/src/main/scala/sbt/internal/Continuous.scala
@@ -1327,7 +1327,10 @@ private[sbt] object ContinuousCommands {
     }
 
   private[sbt] val preWatchCommand = watchCommand(preWatch) { (channel, state) =>
-    watchState(state, channel).beforeCommand(state)
+    val ws = watchState(state, channel)
+    val newState = ws.beforeCommand(state)
+    ws.callbacks.beforeCommand()
+    newState
   }
   private[sbt] val postWatchCommand = watchCommand(postWatch) { (channel, state) =>
     val cs = watchState(state, channel)
diff --git a/sbt/src/sbt-test/watch/before-command/build.sbt b/sbt/src/sbt-test/watch/before-command/build.sbt
new file mode 100644
index 000000000..34d88a1f9
--- /dev/null
+++ b/sbt/src/sbt-test/watch/before-command/build.sbt
@@ -0,0 +1,5 @@
+import java.nio.file.{ Files, Paths }
+
+watchBeforeCommand := { () => Files.write(Paths.get("foo"), "foo".getBytes) }
+
+watchOnIteration := { (_, _, _) => sbt.nio.Watch.CancelWatch }
diff --git a/sbt/src/sbt-test/watch/before-command/test b/sbt/src/sbt-test/watch/before-command/test
new file mode 100644
index 000000000..5bfcff311
--- /dev/null
+++ b/sbt/src/sbt-test/watch/before-command/test
@@ -0,0 +1,3 @@
+> ~compile
+
+$ exists foo