feat: Add JUnit5 extension for OpenFeature (#888)

Signed-off-by: Simon Schrottner <simon.schrottner@dynatrace.com>

.github/component_owners.yml

@@ -1,5 +1,7 @@
 # Keep all in alphabetical order
 components:
+  tools/junit-openfeature:
+    - aepfli
   hooks/open-telemetry:
     - beeme1mr
     - Kavindu-Dodan

.release-please-manifest.json

@@ -8,5 +8,6 @@
   "providers/unleash": "0.0.4-alpha",
   "providers/flipt": "0.0.2",
   "providers/configcat": "0.0.3",
-  "providers/statsig": "0.0.4"
-}
+  "providers/statsig": "0.0.4",
+  "tools/junit-openfeature": "0.0.0"
+}

pom.xml

@@ -28,6 +28,7 @@
 
     <modules>
         <module>hooks/open-telemetry</module>
+        <module>tools/junit-openfeature</module>
         <module>providers/flagd</module>
         <module>providers/flagsmith</module>
         <module>providers/go-feature-flag</module>

release-please-config.json

@@ -110,6 +110,17 @@
         "pom.xml",
         "README.md"
       ]
+    },
+    "tools/junit-openfeature": {
+      "package-name": "dev.openfeature.contrib.tools.junitopenfeature",
+      "release-type": "simple",
+      "bump-minor-pre-major": true,
+      "bump-patch-for-minor-pre-major": true,
+      "versioning": "default",
+      "extra-files": [
+        "pom.xml",
+        "README.md"
+      ]
     }
   },
   "changelog-sections": [

tools/junit-openfeature/README.md

@@ -0,0 +1,141 @@
+# JUnit Open Feature extension
+
+A JUnit5 extension to reduce boilerplate code for testing code which utilizes OpenFeature.
+
+## Getting Started
+
+We are supporting two different flavors for testing, a [simple](#simple-configuration) and an [extended](#extended-configuration) configuration.
+
+Notice: We are most likely not multithread compatible!
+### Simple Configuration
+
+Choose the simple configuration if you are only testing in one domain.
+Per default, it will be used in the global domain.
+
+```java
+@Test
+@Flag(name = "BOOLEAN_FLAG", value = "true")
+void test() {
+    // your test code
+}
+``` 
+
+#### Multiple flags
+
+The `@Flag` annotation can be also repeated multiple times.
+
+```java
+@Test
+@Flag(name = "BOOLEAN_FLAG", value = "true")
+@Flag(name = "BOOLEAN_FLAG2", value = "true")
+void test() {
+    // your test code
+}
+``` 
+
+#### Defining Flags for a whole test-class
+
+`@Flags` can be defined on the class-level too, but method-level
+annotations will supersede class-level annotations.
+
+```java
+@Flag(name = "BOOLEAN_FLAG", value = "true")
+@Flag(name = "BOOLEAN_FLAG2", value = "false")
+class Test {
+    @Test
+    @Flag(name = "BOOLEAN_FLAG2", value = "true") // will be used
+    void test() {
+        // your test code
+    }
+}
+``` 
+
+#### Setting a different domain
+
+You can define your own domain on the test-class-level with `@OpenFeatureDefaultDomain` like:
+
+```java
+@OpenFeatureDefaultDomain("domain")
+class Test {
+    @Test
+    @Flag(name = "BOOLEAN_FLAG", value = "true")
+        // this flag will be available in the `domain` domain
+    void test() {
+        // your test code
+    }
+}
+```
+
+### Extended Configuration
+
+Use the extended configuration when your code needs to use multiple domains.
+
+```java
+@Test
+@OpenFeature({
+        @Flag(name = "BOOLEAN_FLAG", value = "true")
+})
+@OpenFeature(
+        domain = "domain",
+        value = {
+            @Flag(name = "BOOLEAN_FLAG2", value = "true")
+        })
+void test() {
+    // your test code
+}
+``` 
+
+
+#### Multiple flags
+
+The `@Flag` annotation can be also repeated multiple times.
+
+```java
+@Test
+@OpenFeature({
+        @Flag(name = "BOOLEAN_FLAG", value = "true"),
+        @Flag(name = "BOOLEAN_FLAG2", value = "true")
+})
+void test() {
+    // your test code
+}
+``` 
+
+#### Defining Flags for a whole test-class
+
+`@Flag` can be defined on the class-level too, but method-level
+annotations will superseded class-level annotations.
+
+```java
+@OpenFeature({
+        @Flag(name = "BOOLEAN_FLAG", value = "true"),
+        @Flag(name = "BOOLEAN_FLAG2", value = "false")
+})
+class Test {
+    @Test
+    @OpenFeature({
+            @Flag(name = "BOOLEAN_FLAG2", value = "true") // will be used
+    })
+    void test() {
+        // your test code
+    }
+}
+``` 
+
+#### Setting a different domain
+
+You can define an own domain for each usage of the `@OpenFeature` annotation with the `domain` property:
+
+```java
+@Test
+@OpenFeature(
+    domain = "domain",
+    value = {
+        @Flag(name = "BOOLEAN_FLAG2", value = "true") // will be used
+})
+    // this flag will be available in the `domain` domain
+void test() {
+    // your test code
+}
+```
+

tools/junit-openfeature/pom.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>dev.openfeature.contrib</groupId>
+        <artifactId>parent</artifactId>
+        <version>0.1.0</version>
+        <relativePath>../../pom.xml</relativePath>
+    </parent>
+    <groupId>dev.openfeature.contrib.tools</groupId>
+    <artifactId>junitopenfeature</artifactId>
+    <version>0.0.0</version> <!--x-release-please-version -->
+
+    <name>junit-openfeature-extension</name>
+    <description>JUnit5 Extension for OpenFeature</description>
+    <url>https://openfeature.dev</url>
+
+    <developers>
+        <developer>
+            <id>aepfli</id>
+            <name>Simon Schrottner</name>
+            <organization>OpenFeature</organization>
+            <url>https://openfeature.dev/</url>
+        </developer>
+    </developers>
+
+    <dependencies>
+        <dependency>
+            <groupId>dev.openfeature</groupId>
+            <artifactId>sdk</artifactId>
+            <version>[1.4,2.0)</version>
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit.jupiter.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit-pioneer</groupId>
+            <artifactId>junit-pioneer</artifactId>
+            <version>1.9.1</version>
+        </dependency>
+    </dependencies>
+
+</project>

tools/junit-openfeature/src/main/java/dev/openfeature/contrib/tools/junitopenfeature/Flag.java

@@ -0,0 +1,36 @@
+package dev.openfeature.contrib.tools.junitopenfeature;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation for Flag Configuration for the default domain.
+ * Can be used as a standalone flag configuration but also within {@link OpenFeature}.
+ */
+@Target({ElementType.METHOD, ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@Repeatable(Flags.class)
+@ExtendWith(OpenFeatureExtension.class)
+public @interface Flag {
+    /**
+     * The key of the FeatureFlag.
+     */
+    String name();
+
+    /**
+     * The value of the FeatureFlag.
+     */
+    String value();
+
+    /**
+     * The type of the FeatureFlag.
+     */
+    Class<?> valueType() default Boolean.class;
+}
+
+

tools/junit-openfeature/src/main/java/dev/openfeature/contrib/tools/junitopenfeature/Flags.java

@@ -0,0 +1,23 @@
+package dev.openfeature.contrib.tools.junitopenfeature;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Collection of {@link Flag} configurations.
+ */
+@Target({ElementType.METHOD, ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@ExtendWith(OpenFeatureExtension.class)
+public @interface Flags {
+    /**
+     * Collection of {@link Flag} configurations.
+     */
+    Flag[] value() default {};
+}
+
+

tools/junit-openfeature/src/main/java/dev/openfeature/contrib/tools/junitopenfeature/OpenFeature.java

@@ -0,0 +1,30 @@
+package dev.openfeature.contrib.tools.junitopenfeature;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation for generating an extended configuration for OpenFeature.
+ * This annotation allows you to specify a list of flags for a specific domain.
+ */
+@Target({ ElementType.METHOD, ElementType.TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+@Repeatable(value = OpenFeatures.class)
+@ExtendWith(OpenFeatureExtension.class)
+public @interface OpenFeature {
+    /**
+     * the provider domain used for this configuration.
+     */
+    String domain() default "";
+    /**
+     * Collection of {@link Flag} configurations for this domain.
+     */
+    Flag[] value();
+}
+
+

tools/junit-openfeature/src/main/java/dev/openfeature/contrib/tools/junitopenfeature/OpenFeatureDefaultDomain.java

@@ -0,0 +1,23 @@
+package dev.openfeature.contrib.tools.junitopenfeature;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Configuration of a default domain for standalone {@link Flag} configurations.
+ */
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@ExtendWith(OpenFeatureExtension.class)
+public @interface OpenFeatureDefaultDomain {
+    /**
+     * the default domain.
+     */
+    String value() default "";
+}
+
+