diff --git a/bin/install-wp-tests.sh b/bin/install-wp-tests.sh
index 1cd99ed0..6341bdca 100755
--- a/bin/install-wp-tests.sh
+++ b/bin/install-wp-tests.sh
@@ -12,21 +12,43 @@ DB_HOST=${4-localhost}
 WP_VERSION=${5-latest}
 SKIP_DB_CREATE=${6-false}
 
-WP_TESTS_DIR=${WP_TESTS_DIR-/tmp/wordpress-tests-lib}
-WP_CORE_DIR=${WP_CORE_DIR-/tmp/wordpress/}
+TMPDIR=${TMPDIR-/tmp}
+TMPDIR=$(echo $TMPDIR | sed -e "s/\/$//")
+WP_TESTS_DIR=${WP_TESTS_DIR-$TMPDIR/wordpress-tests-lib}
+WP_CORE_DIR=${WP_CORE_DIR-$TMPDIR/wordpress}
 
-command_exists() {
-	type -t "$1" >/dev/null 2>&1
-}
 download() {
-    if command_exists "curl"; then
-        curl -s -o "${2:--}" "$1"
-    elif command_exists "wget"; then
-		wget -nv -O "${2:--}" "$1"
+    if [ `which curl` ]; then
+        curl -s "$1" > "$2";
+    elif [ `which wget` ]; then
+        wget -nv -O "$2" "$1"
+    else
+        echo "Error: Neither curl nor wget is installed."
+        exit 1
     fi
 }
-if [[ $WP_VERSION =~ [0-9]+\.[0-9]+(\.[0-9]+)? ]]; then
-	WP_TESTS_TAG="tags/$WP_VERSION"
+
+# Check if svn is installed
+check_svn_installed() {
+    if ! command -v svn > /dev/null; then
+        echo "Error: svn is not installed. Please install svn and try again."
+        exit 1
+    fi
+}
+
+if [[ $WP_VERSION =~ ^[0-9]+\.[0-9]+\-(beta|RC)[0-9]+$ ]]; then
+	WP_BRANCH=${WP_VERSION%\-*}
+	WP_TESTS_TAG="branches/$WP_BRANCH"
+
+elif [[ $WP_VERSION =~ ^[0-9]+\.[0-9]+$ ]]; then
+	WP_TESTS_TAG="branches/$WP_VERSION"
+elif [[ $WP_VERSION =~ [0-9]+\.[0-9]+\.[0-9]+ ]]; then
+	if [[ $WP_VERSION =~ [0-9]+\.[0-9]+\.[0] ]]; then
+		# version x.x.0 means the first release of the major version, so strip off the .0 and download version x.x
+		WP_TESTS_TAG="tags/${WP_VERSION%??}"
+	else
+		WP_TESTS_TAG="tags/$WP_VERSION"
+	fi
 elif [[ $WP_VERSION == 'nightly' || $WP_VERSION == 'trunk' ]]; then
 	WP_TESTS_TAG="trunk"
 else
@@ -40,10 +62,8 @@ else
 	fi
 	WP_TESTS_TAG="tags/$LATEST_VERSION"
 fi
-
 set -ex
 
-
 install_wp() {
 
 	if [ -d $WP_CORE_DIR ]; then
@@ -53,27 +73,44 @@ install_wp() {
 	mkdir -p $WP_CORE_DIR
 
 	if [[ $WP_VERSION == 'nightly' || $WP_VERSION == 'trunk' ]]; then
-		mkdir -p /tmp/wordpress-nightly
-		download https://wordpress.org/nightly-builds/wordpress-latest.zip  /tmp/wordpress-nightly/wordpress-nightly.zip
-		unzip -q /tmp/wordpress-nightly/wordpress-nightly.zip -d /tmp/wordpress-nightly/
-		mv /tmp/wordpress-nightly/wordpress/* $WP_CORE_DIR
+		mkdir -p $TMPDIR/wordpress-trunk
+		rm -rf $TMPDIR/wordpress-trunk/*
+        check_svn_installed
+		svn export --quiet https://core.svn.wordpress.org/trunk $TMPDIR/wordpress-trunk/wordpress
+		mv $TMPDIR/wordpress-trunk/wordpress/* $WP_CORE_DIR
 	else
 		if [ $WP_VERSION == 'latest' ]; then
 			local ARCHIVE_NAME='latest'
+		elif [[ $WP_VERSION =~ [0-9]+\.[0-9]+ ]]; then
+			# https serves multiple offers, whereas http serves single.
+			download https://api.wordpress.org/core/version-check/1.7/ $TMPDIR/wp-latest.json
+			if [[ $WP_VERSION =~ [0-9]+\.[0-9]+\.[0] ]]; then
+				# version x.x.0 means the first release of the major version, so strip off the .0 and download version x.x
+				LATEST_VERSION=${WP_VERSION%??}
+			else
+				# otherwise, scan the releases and get the most up to date minor version of the major release
+				local VERSION_ESCAPED=`echo $WP_VERSION | sed 's/\./\\\\./g'`
+				LATEST_VERSION=$(grep -o '"version":"'$VERSION_ESCAPED'[^"]*' $TMPDIR/wp-latest.json | sed 's/"version":"//' | head -1)
+			fi
+			if [[ -z "$LATEST_VERSION" ]]; then
+				local ARCHIVE_NAME="wordpress-$WP_VERSION"
+			else
+				local ARCHIVE_NAME="wordpress-$LATEST_VERSION"
+			fi
 		else
 			local ARCHIVE_NAME="wordpress-$WP_VERSION"
 		fi
-		download https://wordpress.org/${ARCHIVE_NAME}.tar.gz  /tmp/wordpress.tar.gz
-		tar --strip-components=1 -zxmf /tmp/wordpress.tar.gz -C $WP_CORE_DIR
+		download https://wordpress.org/${ARCHIVE_NAME}.tar.gz  $TMPDIR/wordpress.tar.gz
+		tar --strip-components=1 -zxmf $TMPDIR/wordpress.tar.gz -C $WP_CORE_DIR
 	fi
 
-	download https://raw.github.com/markoheijnen/wp-mysqli/master/db.php $WP_CORE_DIR/wp-content/db.php
+	download https://raw.githubusercontent.com/markoheijnen/wp-mysqli/master/db.php $WP_CORE_DIR/wp-content/db.php
 }
 
 install_test_suite() {
 	# portable in-place argument for both GNU sed and Mac OSX sed
 	if [[ $(uname -s) == 'Darwin' ]]; then
-		local ioption='-i .bak'
+		local ioption='-i.bak'
 	else
 		local ioption='-i'
 	fi
@@ -82,8 +119,10 @@ install_test_suite() {
 	if [ ! -d $WP_TESTS_DIR ]; then
 		# set up testing suite
 		mkdir -p $WP_TESTS_DIR
-		svn co --quiet https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/includes/ $WP_TESTS_DIR/includes
-		svn co --quiet https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/data/ $WP_TESTS_DIR/data
+		rm -rf $WP_TESTS_DIR/{includes,data}
+        check_svn_installed
+		svn export --quiet --ignore-externals https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/includes/ $WP_TESTS_DIR/includes
+		svn export --quiet --ignore-externals https://develop.svn.wordpress.org/${WP_TESTS_TAG}/tests/phpunit/data/ $WP_TESTS_DIR/data
 	fi
 
 	if [ ! -f wp-tests-config.php ]; then
@@ -91,6 +130,7 @@ install_test_suite() {
 		# remove all forward slashes in the end
 		WP_CORE_DIR=$(echo $WP_CORE_DIR | sed "s:/\+$::")
 		sed $ioption "s:dirname( __FILE__ ) . '/src/':'$WP_CORE_DIR/':" "$WP_TESTS_DIR"/wp-tests-config.php
+		sed $ioption "s:__DIR__ . '/src/':'$WP_CORE_DIR/':" "$WP_TESTS_DIR"/wp-tests-config.php
 		sed $ioption "s/youremptytestdbnamehere/$DB_NAME/" "$WP_TESTS_DIR"/wp-tests-config.php
 		sed $ioption "s/yourusernamehere/$DB_USER/" "$WP_TESTS_DIR"/wp-tests-config.php
 		sed $ioption "s/yourpasswordhere/$DB_PASS/" "$WP_TESTS_DIR"/wp-tests-config.php
@@ -99,6 +139,23 @@ install_test_suite() {
 
 }
 
+recreate_db() {
+	shopt -s nocasematch
+	if [[ $1 =~ ^(y|yes)$ ]]
+	then
+		mysqladmin drop $DB_NAME -f --user="$DB_USER" --password="$DB_PASS"$EXTRA
+		create_db
+		echo "Recreated the database ($DB_NAME)."
+	else
+		echo "Leaving the existing database ($DB_NAME) in place."
+	fi
+	shopt -u nocasematch
+}
+
+create_db() {
+	mysqladmin create $DB_NAME --user="$DB_USER" --password="$DB_PASS"$EXTRA
+}
+
 install_db() {
 
 	if [ ${SKIP_DB_CREATE} = "true" ]; then
@@ -122,7 +179,14 @@ install_db() {
 	fi
 
 	# create database
-	mysql --user="$DB_USER" --password="$DB_PASS"$EXTRA --execute "CREATE DATABASE IF NOT EXISTS $DB_NAME;"
+	if [ $(mysql --user="$DB_USER" --password="$DB_PASS"$EXTRA --execute='show databases;' | grep ^$DB_NAME$) ]
+	then
+		echo "Reinstalling will delete the existing test database ($DB_NAME)"
+		read -p 'Are you sure you want to proceed? [y/N]: ' DELETE_EXISTING_DB
+		recreate_db $DELETE_EXISTING_DB
+	else
+		create_db
+	fi
 }
 
 install_wp