Simplify test matrix and test setup

.travis.yml

@@ -1,28 +1,27 @@
 language: php
 
-php:
-# - 5.3 # requires old distro
-  - 5.4
-  - 5.5
-  - 5.6
-  - 7.0
-  - 7.1
-  - 7.2
-  - 7.3
-  - 7.4
-  - nightly # ignore errors, see below
-  - hhvm # ignore errors, see below
-
 # lock distro so new future defaults will not break the build
 dist: trusty
 
 matrix:
   include:
     - php: 5.3
       dist: precise
+    - php: 5.4
+    - php: 5.5
+    - php: 5.6
+    - php: 7.0
+    - php: 7.1
+    - php: 7.2
+    - php: 7.3
+    - php: 7.4
+    - php: nightly
+    - php: hhvm-3.18
+      install:
+        - composer require phpunit/phpunit:^5 --dev --no-interaction # requires legacy phpunit
   allow_failures:
     - php: nightly
-    - php: hhvm
+    - php: hhvm-3.18
 
 install:
   - composer install --no-interaction

composer.json

@@ -21,5 +21,10 @@
         "psr-4": {
             "React\\HttpClient\\": "src"
         }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "React\\Tests\\HttpClient\\": "tests"
+        }
     }
 }

phpunit.xml.dist

@@ -8,7 +8,7 @@
          convertWarningsToExceptions="true"
          processIsolation="false"
          stopOnFailure="false"
-         bootstrap="tests/bootstrap.php"
+         bootstrap="vendor/autoload.php"
 >
     <testsuites>
         <testsuite name="React Test Suite">