Update install-wp-tests.sh and .travix.yml

The old version of the install-wp-tests.sh script would only install
the latest stable version. This update uses the latest template from
WP-CLI, which includes support for testing against trunk.

.travis.yml

@@ -9,8 +9,8 @@ php:
     - 7.0
 
 env:
-    - WP_VERSION=latest WP_MULTISITE=0
-    - WP_VERSION=latest WP_MULTISITE=1
+    - WP_VERSION=trunk WP_MULTISITE=0
+    - WP_VERSION=trunk WP_MULTISITE=1
     - WP_VERSION=4.3 WP_MULTISITE=0
     - WP_VERSION=4.3 WP_MULTISITE=1
     - WP_VERSION=4.2 WP_MULTISITE=0

bin/install-wp-tests.sh

@@ -24,6 +24,8 @@ download() {
 
 if [[ $WP_VERSION =~ [0-9]+\.[0-9]+(\.[0-9]+)? ]]; then
 	WP_TESTS_TAG="tags/$WP_VERSION"
+elif [[ $WP_VERSION == 'nightly' || $WP_VERSION == 'trunk' ]]; then
+	WP_TESTS_TAG="trunk"
 else
 	# http serves a single offer, whereas https serves multiple. we only want one
 	download http://api.wordpress.org/core/version-check/1.7/ /tmp/wp-latest.json
@@ -46,15 +48,21 @@ install_wp() {
 
 	mkdir -p $WP_CORE_DIR
 
-	if [ $WP_VERSION == 'latest' ]; then
-		local ARCHIVE_NAME='latest'
+	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/* $WP_CORE_DIR
 	else
-		local ARCHIVE_NAME="wordpress-$WP_VERSION"
+		if [ $WP_VERSION == 'latest' ]; then
+			local ARCHIVE_NAME='latest'
+		else
+			local ARCHIVE_NAME="wordpress-$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
 	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://raw.github.com/markoheijnen/wp-mysqli/master/db.php $WP_CORE_DIR/wp-content/db.php
 }