fix: use config fallback for appName and environment (#70)

Author: kwasniew

src/main/kotlin/io/getunleash/UnleashClient.kt

@@ -48,14 +48,14 @@ class UnleashClient(
             unleashFetcher = fetcher,
             cache = cache,
             config = unleashConfig,
-            context = unleashContext,
+            context = this.getContext(),
             unleashConfig.pollingMode
         )
         is FilePollingMode -> FilePollingPolicy(
             unleashFetcher = fetcher,
             cache = cache,
             config = unleashConfig,
-            context = unleashContext,
+            context = this.getContext(),
             unleashConfig.pollingMode
         )
         else -> throw InvalidParameterException("The polling mode parameter is invalid")
@@ -98,13 +98,16 @@ class UnleashClient(
     }
 
     override fun updateContext(context: UnleashContext): CompletableFuture<Void> {
-        refreshPolicy.context = context
         this.unleashContext = context
+        refreshPolicy.context = this.getContext()
         return refreshPolicy.refreshAsync()
     }
 
     override fun getContext(): UnleashContext {
-        return unleashContext
+        return unleashContext.copy(
+                appName = unleashContext.appName ?: unleashConfig.appName,
+                environment = unleashContext.environment ?: unleashConfig.environment
+        )
     }
 
     override fun close() {

src/test/kotlin/io/getunleash/UnleashClientTest.kt

@@ -188,4 +188,32 @@ class UnleashClientTest {
             assertThat(updatedFuture).succeedsWithin(Duration.ofSeconds(2))
         }
     }
+
+    @Test
+    fun `Context falls back to config values for appName and environment when not provided`() {
+        val fallbackConfig = config.newBuilder().appName("fallbackApp").environment("fallbackEnv").build()
+        val incompleteContext = UnleashContext.newBuilder().userId("someUserId").build()
+
+        UnleashClient.newBuilder().unleashConfig(fallbackConfig).unleashContext(incompleteContext).build().use { client ->
+            val usedContext = client.getContext()
+
+            assertThat(usedContext.appName).isEqualTo("fallbackApp")
+            assertThat(usedContext.environment).isEqualTo("fallbackEnv")
+            assertThat(usedContext.userId).isEqualTo("someUserId")
+        }
+    }
+
+    @Test
+    fun `Explicit context takes precedence over config appName and environment`() {
+        val fallbackConfig = config.newBuilder().appName("fallbackApp").environment("fallbackEnv").build()
+        val explicitContext = UnleashContext.newBuilder().appName("contextApp").environment("contextEnvironment").build()
+
+        UnleashClient.newBuilder().unleashConfig(fallbackConfig).unleashContext(explicitContext).build().use { client ->
+            val usedContext = client.getContext()
+
+            assertThat(usedContext.appName).isEqualTo("contextApp")
+            assertThat(usedContext.environment).isEqualTo("contextEnvironment")
+        }
+    }
+
 }