Rename serial number environment variable to ANDROID_SERIAL

Bug: 148303078
Test: unit tests
Change-Id: I9cdfc5dde63e85866cb47fce9b80c6b7ab23103b
diff --git a/test_framework/com/android/tradefed/targetprep/RunHostScriptTargetPreparer.java b/test_framework/com/android/tradefed/targetprep/RunHostScriptTargetPreparer.java
index 346c86e..0245523 100644
--- a/test_framework/com/android/tradefed/targetprep/RunHostScriptTargetPreparer.java
+++ b/test_framework/com/android/tradefed/targetprep/RunHostScriptTargetPreparer.java
@@ -42,7 +42,7 @@
 
 /**
  * Target preparer which executes a script before running a test. The script can reference the
- * device's serial number using the SERIAL environment variable.
+ * device's serial number using the ANDROID_SERIAL environment variable.
  */
 @OptionClass(alias = "run-host-script")
 public class RunHostScriptTargetPreparer extends BaseTargetPreparer {
@@ -79,7 +79,7 @@
 
         // Set working directory and environment variables
         getRunUtil().setWorkingDir(mWorkDir);
-        getRunUtil().setEnvVariable("SERIAL", device.getSerialNumber());
+        getRunUtil().setEnvVariable("ANDROID_SERIAL", device.getSerialNumber());
         setPathVariable(testInfo);
 
         // Execute script and handle result
diff --git a/tests/src/com/android/tradefed/targetprep/RunHostScriptTargetPreparerTest.java b/tests/src/com/android/tradefed/targetprep/RunHostScriptTargetPreparerTest.java
index ee43e22..4125fa1 100644
--- a/tests/src/com/android/tradefed/targetprep/RunHostScriptTargetPreparerTest.java
+++ b/tests/src/com/android/tradefed/targetprep/RunHostScriptTargetPreparerTest.java
@@ -112,7 +112,7 @@
         mOptionSetter.setOptionValue("script-timeout", "10");
         // Verify environment, timeout, and script path
         mPreparer.setUp(mTestInfo);
-        verify(mRunUtil).setEnvVariable("SERIAL", DEVICE_SERIAL);
+        verify(mRunUtil).setEnvVariable("ANDROID_SERIAL", DEVICE_SERIAL);
         verify(mRunUtil, never()).setEnvVariable(eq("PATH"), any()); // uses default PATH
         verify(mRunUtil).runTimedCmd(10L, mScriptFile.getAbsolutePath());
         // Verify that script is executable