Add TestResourcesRule

tester/build.gradle

@@ -1,12 +1,11 @@
 apply plugin: 'java-library'
 dependencies {
-    implementation 'commons-io:commons-io:2.6'
-
-    testImplementation 'junit:junit:4.12'
-    testImplementation 'commons-io:commons-io:2.6'
-    testImplementation 'com.google.truth:truth:1.0.1'
-    testImplementation 'com.google.code.gson:gson:2.8.5'
-    testImplementation 'org.mockito:mockito-core:2.28.2'
+  implementation 'junit:junit:4.13.1'
+  implementation 'commons-io:commons-io:2.6'
+  testImplementation 'commons-io:commons-io:2.6'
+  testImplementation 'com.google.truth:truth:1.0.1'
+  testImplementation 'com.google.code.gson:gson:2.8.6'
+  testImplementation 'org.mockito:mockito-core:3.3.3'
 
 }
 

tester/src/main/java/io/github/android/tang/tony/test/util/TestResourcesRule.java

@@ -0,0 +1,25 @@
+package io.github.android.tang.tony.test.util;
+
+import java.io.InputStream;
+import org.junit.rules.ExternalResource;
+
+public class TestResourcesRule extends ExternalResource {
+
+  String resourceFilePath;
+
+  public TestResourcesRule(String resourceFilePath) {
+    this.resourceFilePath = resourceFilePath;
+  }
+
+  public String content() {
+    return content("utf-8");
+  }
+
+  public String content(String charSet) {
+    return TestUtil.content(resourceFilePath, charSet, this);
+  }
+
+  public InputStream inputStream() {
+    return getClass().getResourceAsStream(resourceFilePath);
+  }
+}

tester/src/test/java/io/github/android/tang/tony/test/util/TestUtilsTest.java

@@ -6,14 +6,17 @@
 import java.lang.reflect.Type;
 import java.util.HashMap;
 import java.util.Map;
+import org.junit.Rule;
 import org.junit.Test;
 
 public class TestUtilsTest {
 
+  @Rule public TestResourcesRule resource = new TestResourcesRule("gson.json");
+
   @Test
   public void content() {
 
-    String json = TestUtil.content("gson.json", this);
+    String json = resource.content();
     Type type = new TypeToken<Map<String, Integer>>() {}.getType();
     Map<String, Integer> t = new Gson().fromJson(json, type);
     Truth.assertThat(t).isEqualTo(expected());