From f4294371aeda31d28fa712e1e20506dd547adb18 Mon Sep 17 00:00:00 2001
From: Kevin Brolly <kevin.brolly@gmail.com>
Date: Thu, 17 Oct 2019 13:55:52 +0100
Subject: [PATCH 1/7] Cache the STACK in use and use it to bust cache if it
 changes

---
 bin/compile | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/bin/compile b/bin/compile
index fb494c6..bbe505e 100755
--- a/bin/compile
+++ b/bin/compile
@@ -29,6 +29,13 @@ function indent() {
   esac
 }
 
+# Store which STACK we are running on in the cache to bust the cache if it changes
+if [ -f $CACHE_DIR/.apt/STACK ]; then
+  CACHED_STACK=$(cat "$CACHE_DIR/.apt/STACK")
+else
+  CACHED_STACK=$STACK
+fi
+
 APT_CACHE_DIR="$CACHE_DIR/apt/cache"
 APT_STATE_DIR="$CACHE_DIR/apt/state"
 APT_SOURCELIST_DIR="$CACHE_DIR/apt/sources"   # place custom sources.list here
@@ -42,7 +49,7 @@ case "$APT_VERSION" in
   *)         APT_FORCE_YES="--allow-downgrades --allow-remove-essential --allow-change-held-packages";;
 esac
 
-if [ -f $APT_CACHE_DIR/Aptfile ] && cmp -s $BUILD_DIR/Aptfile $APT_CACHE_DIR/Aptfile ; then
+if [ -f $APT_CACHE_DIR/Aptfile ] && cmp -s $BUILD_DIR/Aptfile $APT_CACHE_DIR/Aptfile && [[ $CACHED_STACK == $STACK ]] ; then
   # Old Aptfile is the same as new
   topic "Reusing cache"
 else
@@ -112,3 +119,6 @@ export | grep -E -e ' (PATH|LD_LIBRARY_PATH|LIBRARY_PATH|INCLUDE_PATH|CPATH|CPPP
 
 topic "Rewrite package-config files"
 find $BUILD_DIR/.apt -type f -ipath '*/pkgconfig/*.pc' | xargs --no-run-if-empty -n 1 sed -i -e 's!^prefix=\(.*\)$!prefix='"$BUILD_DIR"'/.apt\1!g'
+
+# Store which STACK we are running on in the cache to bust the cache if it changes
+echo "$STACK" > "$CACHE_DIR/.apt/STACK"
\ No newline at end of file

From 5135ddfc0eb211b605a29cd7a64af8d9f364126c Mon Sep 17 00:00:00 2001
From: Kevin Brolly <kevin.brolly@gmail.com>
Date: Thu, 17 Oct 2019 13:58:24 +0100
Subject: [PATCH 2/7] Refactored tests and added fixtures to make future tests
 easier

---
 test/compile_test.sh          | 10 +++++-----
 test/fixtures/Aptfile/Aptfile |  3 +++
 2 files changed, 8 insertions(+), 5 deletions(-)
 create mode 100644 test/fixtures/Aptfile/Aptfile

diff --git a/test/compile_test.sh b/test/compile_test.sh
index a742ab5..052bcc2 100644
--- a/test/compile_test.sh
+++ b/test/compile_test.sh
@@ -3,11 +3,7 @@
 . ${BUILDPACK_TEST_RUNNER_HOME}/lib/test_utils.sh
 
 testCompile() {
-  cat > ${BUILD_DIR}/Aptfile <<EOF
-# Test comment
-s3cmd
-wget
-EOF
+  loadFixture "Aptfile"
 
   compile
 
@@ -18,3 +14,7 @@ EOF
   assertCaptured "Fetching .debs for wget"
   assertCaptured "Installing wget_"
 }
+
+loadFixture() {
+  cp -a $BUILDPACK_HOME/test/fixtures/$1/. ${BUILD_DIR}
+}
\ No newline at end of file
diff --git a/test/fixtures/Aptfile/Aptfile b/test/fixtures/Aptfile/Aptfile
new file mode 100644
index 0000000..b24b956
--- /dev/null
+++ b/test/fixtures/Aptfile/Aptfile
@@ -0,0 +1,3 @@
+# Test comment
+s3cmd
+wget
\ No newline at end of file

From d27a66b0d8ec058bba0fe4d153919945d48aad27 Mon Sep 17 00:00:00 2001
From: Kevin Brolly <kevin.brolly@gmail.com>
Date: Thu, 17 Oct 2019 13:59:10 +0100
Subject: [PATCH 3/7] Added tests for new stack cache busting feature

---
 test/compile_test.sh | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/test/compile_test.sh b/test/compile_test.sh
index 052bcc2..f0da86e 100644
--- a/test/compile_test.sh
+++ b/test/compile_test.sh
@@ -15,6 +15,36 @@ testCompile() {
   assertCaptured "Installing wget_"
 }
 
+testStackChange() {
+  loadFixture "Aptfile"
+
+  #Set the cached STACK value to a non-existent stack, so it is guaranteed to change.
+  mkdir -p "$CACHE_DIR/.apt/"
+  echo "cedar-10" > "$CACHE_DIR/.apt/STACK"
+  
+  #Load the Aptfile into the cache, to exclusively test the stack changes
+  mkdir -p "$CACHE_DIR/apt/cache"
+  cp $BUILD_DIR/Aptfile "$CACHE_DIR/apt/cache"
+
+  compile
+
+  assertCapturedSuccess
+
+  assertCaptured "Detected Aptfile or Stack changes, flushing cache"
+}
+
+testStackNoChange() {
+  loadFixture "Aptfile"
+
+  #Load the Aptfile into the cache, to exclusively test the stack changes
+  mkdir -p "$CACHE_DIR/apt/cache"
+  cp $BUILD_DIR/Aptfile "$CACHE_DIR/apt/cache"
+
+  compile
+
+  assertCaptured "Reusing cache"
+}
+
 loadFixture() {
   cp -a $BUILDPACK_HOME/test/fixtures/$1/. ${BUILD_DIR}
 }
\ No newline at end of file

From cf5aceb6921697774f38fa156ae12b7eb2f72b08 Mon Sep 17 00:00:00 2001
From: Kevin Brolly <kevin.brolly@gmail.com>
Date: Thu, 17 Oct 2019 14:22:55 +0100
Subject: [PATCH 4/7] Fixed issue with stack not getting cached

---
 bin/compile | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/bin/compile b/bin/compile
index bbe505e..49c40d9 100755
--- a/bin/compile
+++ b/bin/compile
@@ -34,6 +34,9 @@ if [ -f $CACHE_DIR/.apt/STACK ]; then
   CACHED_STACK=$(cat "$CACHE_DIR/.apt/STACK")
 else
   CACHED_STACK=$STACK
+  # Store the STACK in the cache for next time.
+  mkdir -p "$CACHE_DIR/.apt"
+  echo "$STACK" > "$CACHE_DIR/.apt/STACK"
 fi
 
 APT_CACHE_DIR="$CACHE_DIR/apt/cache"
@@ -119,6 +122,3 @@ export | grep -E -e ' (PATH|LD_LIBRARY_PATH|LIBRARY_PATH|INCLUDE_PATH|CPATH|CPPP
 
 topic "Rewrite package-config files"
 find $BUILD_DIR/.apt -type f -ipath '*/pkgconfig/*.pc' | xargs --no-run-if-empty -n 1 sed -i -e 's!^prefix=\(.*\)$!prefix='"$BUILD_DIR"'/.apt\1!g'
-
-# Store which STACK we are running on in the cache to bust the cache if it changes
-echo "$STACK" > "$CACHE_DIR/.apt/STACK"
\ No newline at end of file

From a20191864cd4a1f2262936119cf3bac061235cef Mon Sep 17 00:00:00 2001
From: Kevin Brolly <kevin.brolly@gmail.com>
Date: Thu, 17 Oct 2019 14:25:40 +0100
Subject: [PATCH 5/7] Added new text for when stack changes

---
 bin/compile | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/bin/compile b/bin/compile
index 49c40d9..b683beb 100755
--- a/bin/compile
+++ b/bin/compile
@@ -53,11 +53,11 @@ case "$APT_VERSION" in
 esac
 
 if [ -f $APT_CACHE_DIR/Aptfile ] && cmp -s $BUILD_DIR/Aptfile $APT_CACHE_DIR/Aptfile && [[ $CACHED_STACK == $STACK ]] ; then
-  # Old Aptfile is the same as new
+  # Old Aptfile is the same as new and STACK has not changed
   topic "Reusing cache"
 else
-  # Aptfile changed or does not exist
-  topic "Detected Aptfile changes, flushing cache"
+  # Aptfile changed or does not exist or STACK changed
+  topic "Detected Aptfile or Stack changes, flushing cache"
   rm -rf $APT_CACHE_DIR
   mkdir -p "$APT_CACHE_DIR/archives/partial"
   mkdir -p "$APT_STATE_DIR/lists/partial"

From 9a1c7b68dd0fd6724f52ef4336222140a669c36b Mon Sep 17 00:00:00 2001
From: Kevin Brolly <kevin.brolly@gmail.com>
Date: Thu, 17 Oct 2019 15:53:02 +0100
Subject: [PATCH 6/7] Fixed issue where STACK was not always cached

---
 bin/compile          |  7 ++++---
 test/compile_test.sh | 11 +++++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/bin/compile b/bin/compile
index b683beb..af544c2 100755
--- a/bin/compile
+++ b/bin/compile
@@ -34,11 +34,12 @@ if [ -f $CACHE_DIR/.apt/STACK ]; then
   CACHED_STACK=$(cat "$CACHE_DIR/.apt/STACK")
 else
   CACHED_STACK=$STACK
-  # Store the STACK in the cache for next time.
-  mkdir -p "$CACHE_DIR/.apt"
-  echo "$STACK" > "$CACHE_DIR/.apt/STACK"
 fi
 
+# Ensure we store the STACK in the cache for next time.
+mkdir -p "$CACHE_DIR/.apt"
+echo "$STACK" > "$CACHE_DIR/.apt/STACK"
+
 APT_CACHE_DIR="$CACHE_DIR/apt/cache"
 APT_STATE_DIR="$CACHE_DIR/apt/state"
 APT_SOURCELIST_DIR="$CACHE_DIR/apt/sources"   # place custom sources.list here
diff --git a/test/compile_test.sh b/test/compile_test.sh
index f0da86e..af95c4b 100644
--- a/test/compile_test.sh
+++ b/test/compile_test.sh
@@ -45,6 +45,17 @@ testStackNoChange() {
   assertCaptured "Reusing cache"
 }
 
+testStackCached() {
+  # Test that we are correctly storing the value of STACK in the cache
+  loadFixture "Aptfile"
+
+  compile
+  assertCapturedSuccess
+
+  CACHED_STACK=$(cat "$CACHE_DIR/.apt/STACK")
+  assertTrue 'STACK not cached' "[[ $CACHED_STACK == $STACK ]]"
+}
+
 loadFixture() {
   cp -a $BUILDPACK_HOME/test/fixtures/$1/. ${BUILD_DIR}
 }
\ No newline at end of file

From 6d2c69f690a060d92e7ccd206a76a013ec100f80 Mon Sep 17 00:00:00 2001
From: Kevin Brolly <kevin.brolly@gmail.com>
Date: Thu, 17 Oct 2019 16:13:56 +0100
Subject: [PATCH 7/7] Fixed test to ensure STACK is cached

---
 test/compile_test.sh | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/test/compile_test.sh b/test/compile_test.sh
index af95c4b..f5c4a40 100644
--- a/test/compile_test.sh
+++ b/test/compile_test.sh
@@ -46,14 +46,12 @@ testStackNoChange() {
 }
 
 testStackCached() {
-  # Test that we are correctly storing the value of STACK in the cache
   loadFixture "Aptfile"
 
   compile
   assertCapturedSuccess
 
-  CACHED_STACK=$(cat "$CACHE_DIR/.apt/STACK")
-  assertTrue 'STACK not cached' "[[ $CACHED_STACK == $STACK ]]"
+  assertTrue 'STACK not cached' "[ -e $CACHE_DIR/.apt/STACK ]"
 }
 
 loadFixture() {