test.py should require that the SDK be activated (#492)

It was working previously by accident because the tests were
using the defaults such as `$HOME/.emscripten`.  However usage of the
emsdk should really only happen in the emsdk environment where
EM_CONFIG dictates the config location (not just using the default).

This change is needed as precursor to making `--embedded` the default
(in this case the config doesn't live in `$HOME/.emscripten`).

.circleci/config.yml

@@ -36,7 +36,11 @@ jobs:
           name: Install debian packages
           command: apt-get update -q && apt-get install -q -y cmake build-essential openjdk-8-jre-headless
       - run: scripts/test.sh
-      - run: scripts/test.py
+      - run:
+          name: test.py
+          command: |
+            source emsdk_env.sh
+            scripts/test.py
   test-mac:
     macos:
       xcode: "9.0"
@@ -54,7 +58,11 @@ jobs:
           name: Install python 3
           command: brew install python3
       - run: scripts/test.sh
-      - run: scripts/test.py
+      - run:
+          name: test.py
+          command: |
+            source emsdk_env.sh
+            scripts/test.py
   test-windows:
     executor:
       name: win/vs2019
@@ -76,7 +84,11 @@ jobs:
           name: Install latest
           shell: cmd.exe
           command: scripts\test.bat
-      - run: python scripts/test.py
+      - run:
+          name: test.py
+          command: |
+            source emsdk_env.sh
+            python scripts/test.py
 
 workflows:
   flake8: