Backport AcademyStepper fix in #4532 to verified branch

.github/workflows/pre-commit.yml

@@ -10,7 +10,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: actions/setup-python@v1
+    - uses: actions/setup-python@v2
+      with:
+        python-version: 3.7.x
     - uses: actions/setup-ruby@v1
       with:
         ruby-version: '2.6'

.yamato/com.unity.ml-agents-test.yml

@@ -3,19 +3,25 @@ test_editors:
     # 2018.4 doesn't support code-coverage
     coverageOptions:
     minCoveragePct: 0
+    # We want some scene tests to run in the DevProject, but packages there only support 2019+
+    testProject: Project
   - version: 2019.3
     coverageOptions: --enable-code-coverage --code-coverage-options 'generateHtmlReport;assemblyFilters:+Unity.ML-Agents'
     minCoveragePct: 72
+    testProject: DevProject
   - version: 2020.1
     coverageOptions: --enable-code-coverage --code-coverage-options 'generateHtmlReport;assemblyFilters:+Unity.ML-Agents'
     minCoveragePct: 72
+    testProject: DevProject
   - version: 2020.2
     coverageOptions: --enable-code-coverage --code-coverage-options 'generateHtmlReport;assemblyFilters:+Unity.ML-Agents'
     minCoveragePct: 72
+    testProject: DevProject
 trunk_editor:
   - version: trunk
     coverageOptions: --enable-code-coverage --code-coverage-options 'generateHtmlReport;assemblyFilters:+Unity.ML-Agents'
     minCoveragePct: 72
+    testProject: DevProject
 test_platforms:
   - name: win
     type: Unity::VM
@@ -61,7 +67,7 @@ test_{{ platform.name }}_{{ editor.version }}:
     flavor: {{ platform.flavor}}
   commands:
     - npm install upm-ci-utils@stable -g --registry https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-npm
-    - upm-ci package test -u {{ editor.version }} --package-path com.unity.ml-agents {{ editor.coverageOptions }}
+    - upm-ci project test -u {{ editor.version }} --project-path {{ editor.testProject }} {{ editor.coverageOptions }} --extra-utr-arg "reruncount=2"
     - python3 ml-agents/tests/yamato/check_coverage_percent.py upm-ci~/test-results/ {{ editor.minCoveragePct }}
   artifacts:
     logs:
@@ -75,6 +81,7 @@ test_{{ platform.name }}_{{ editor.version }}:
     changes:
       only:
         - "com.unity.ml-agents/**"
+        - "{{ editor.testProject }}/**"
         - "ml-agents/tests/yamato/**"
         - ".yamato/com.unity.ml-agents-test.yml"
     {% endif %}
@@ -96,7 +103,7 @@ test_{{ platform.name }}_trunk:
     {% if platform.name == "win" %}
     - upm-ci package test -u "C:\build\output\Unity-Technologies\ml-agents\.Editor" --package-path com.unity.ml-agents {{ editor.coverageOptions }}
     {% else %}
-    - upm-ci package test -u {{ editor.version }} --package-path com.unity.ml-agents {{ editor.coverageOptions }}
+    - upm-ci project test -u {{ editor.version }} --project-path {{ editor.testProject }} {{ editor.coverageOptions }} --extra-utr-arg "reruncount=2"
     {% endif %}
     - python3 ml-agents/tests/yamato/check_coverage_percent.py upm-ci~/test-results/ {{ editor.minCoveragePct }}
   artifacts:

DevProject/Assets/ML-Agents/Scripts/Tests/Runtime/AcademyTest/AcademyStepperTest.cs

@@ -0,0 +1,36 @@
+using System.Collections;
+using NUnit.Framework;
+using UnityEngine.TestTools;
+using UnityEngine;
+using UnityEngine.SceneManagement;
+using Unity.MLAgents;
+#if UNITY_EDITOR
+using UnityEditor.SceneManagement;
+#endif
+
+namespace Tests
+{
+    public class AcademyStepperTest
+    {
+        [SetUp]
+        public void Setup()
+        {
+            SceneManager.LoadScene("ML-Agents/Scripts/Tests/Runtime/AcademyTest/AcademyStepperTestScene");
+        }
+
+        /// <summary>
+        /// Verify in each update, the Academy is only stepped once.
+        /// </summary>
+        [UnityTest]
+        public IEnumerator AcademyStepperCleanupPasses()
+        {
+            var academy = Academy.Instance;
+            int initStepCount = academy.TotalStepCount;
+            for (var i = 0; i < 5; i++)
+            {
+                yield return new WaitForFixedUpdate();
+                Assert.True(academy.TotalStepCount - initStepCount == i + 1);
+            }
+        }
+    }
+}