Update test matrix.

Author: AlekSi

.travis.yml

@@ -5,12 +5,6 @@ language: go
 services:
   - docker
 
-go:
-  - 1.7.x
-  - 1.8.x
-  - 1.9.x
-  - master
-
 env:
   global:
     # See https://github.com/go-sql-driver/mysql/wiki/Testing
@@ -21,18 +15,39 @@ env:
     - MYSQL_TEST_DBNAME=gotest
     - MYSQL_TEST_CONCURRENT=1
 
-  # https://www.mysql.com/support/supportedplatforms/database.html
-  # https://mariadb.org/about/maintenance-policy/
   matrix:
-    - MYSQL_IMAGE=mysql:5.5
-    - MYSQL_IMAGE=mysql:5.6
-    - MYSQL_IMAGE=mysql:5.7
-    # - MYSQL_IMAGE=mysql:8.0
-    - MYSQL_IMAGE=mariadb:5.5
-    - MYSQL_IMAGE=mariadb:10.0
-    - MYSQL_IMAGE=mariadb:10.1
-    - MYSQL_IMAGE=mariadb:10.2
-    - MYSQL_IMAGE=mariadb:10.3
+    include:
+      # test latest stable MySQL (currently 5.7) with 3 latest Go releases + master
+      - go: 1.7.x
+        env: MYSQL_IMAGE=mysql:5.7
+      - go: 1.8.x
+        env: MYSQL_IMAGE=mysql:5.7
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mysql:5.7
+      - go: master
+        env: MYSQL_IMAGE=mysql:5.7
+
+      # test latest stable Go (currently 1.9.x) with all other supported MySQL versions + not yet supported 8.0
+      # https://www.mysql.com/support/supportedplatforms/database.html
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mysql:5.5
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mysql:5.6
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mysql:8.0
+
+      # test latest stable Go (currently 1.9.x) with all supported MariaDB versions + not yet supported 10.3
+      # https://mariadb.org/about/maintenance-policy/
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mariadb:5.5
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mariadb:10.0
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mariadb:10.1
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mariadb:10.2
+      - go: 1.9.x
+        env: MYSQL_IMAGE=mariadb:10.3
 
 go_import_path: github.com/go-sql-driver/mysql