From 7587af8de972785610fa4491f4cfbe033a6fcf50 Mon Sep 17 00:00:00 2001
From: Oleg Anastassov <oleg.anastassov@gmail.com>
Date: Sat, 27 Jul 2024 09:26:58 +0200
Subject: [PATCH] feature control

---
 .../vms/api/internal/FeatureController.java   | 35 +++++++++++
 .../api/internal/FeatureControllerTest.java   | 63 +++++++++++++++++++
 2 files changed, 98 insertions(+)
 create mode 100644 src/main/java/vms/api/internal/FeatureController.java
 create mode 100644 src/test/java/vms/api/internal/FeatureControllerTest.java

diff --git a/src/main/java/vms/api/internal/FeatureController.java b/src/main/java/vms/api/internal/FeatureController.java
new file mode 100644
index 0000000..f3d7de1
--- /dev/null
+++ b/src/main/java/vms/api/internal/FeatureController.java
@@ -0,0 +1,35 @@
+package vms.api.internal;
+
+import static java.util.function.Predicate.not;
+import static java.util.stream.Collectors.toSet;
+
+import java.util.Collection;
+import java.util.Map;
+import java.util.stream.Stream;
+import org.springframework.core.env.Environment;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/internal/feature-control")
+public class FeatureController {
+
+  private final Collection<String> features;
+
+  FeatureController(Environment environment) {
+    var values = environment.getProperty("FEATURE_CONTROL", "").split(",");
+    features = Stream.of(values).map(String::trim).filter(not(String::isBlank)).collect(toSet());
+  }
+
+  @GetMapping
+  Collection<String> getAll() {
+    return features;
+  }
+
+  @GetMapping("/{name}")
+  Map<String, Boolean> getFeature(@PathVariable String name) {
+    return Map.of(name, features.contains(name));
+  }
+}
diff --git a/src/test/java/vms/api/internal/FeatureControllerTest.java b/src/test/java/vms/api/internal/FeatureControllerTest.java
new file mode 100644
index 0000000..f063464
--- /dev/null
+++ b/src/test/java/vms/api/internal/FeatureControllerTest.java
@@ -0,0 +1,63 @@
+package vms.api.internal;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
+
+import java.util.Collection;
+import java.util.Map;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.core.env.Environment;
+
+@ExtendWith(MockitoExtension.class)
+class FeatureControllerTest {
+
+  @Mock Environment environment;
+
+  @BeforeEach
+  void setUp() {
+    when(environment.getProperty("FEATURE_CONTROL", "")).thenReturn("FooEarlyPreview,HideAppBar");
+  }
+
+  @Test
+  void shouldReturnNoFeaturesIfNoEnvironmentPropertySet() {
+    // given
+    when(environment.getProperty("FEATURE_CONTROL", "")).thenReturn("");
+
+    // when
+    Collection<String> features = new FeatureController(environment).getAll();
+
+    // then
+    assertThat(features).isEmpty();
+  }
+
+  @Test
+  void shouldReturnFeaturesIfEnvironmentPropertySet() {
+    // when
+    Collection<String> features = new FeatureController(environment).getAll();
+
+    // then
+    assertThat(features).containsOnly("FooEarlyPreview", "HideAppBar");
+  }
+
+  @Test
+  void shouldReturnFeatureDisabledIfNoFeaturePresent() {
+    // when
+    Map<String, Boolean> feature = new FeatureController(environment).getFeature("NewUI");
+
+    // then
+    assertThat(feature).containsExactly(Map.entry("NewUI", false));
+  }
+
+  @Test
+  void shouldReturnFeatureEnabledIfFeaturePresent() {
+    // when
+    Map<String, Boolean> feature = new FeatureController(environment).getFeature("HideAppBar");
+
+    // then
+    assertThat(feature).containsExactly(Map.entry("HideAppBar", true));
+  }
+}