Added ECS credentials provider test for local full URI

aws-runtime/aws-config/common/test/aws/sdk/kotlin/runtime/auth/credentials/EcsCredentialsProviderTest.kt

@@ -138,6 +138,26 @@ class EcsCredentialsProviderTest {
         }.message.shouldContain("The container credentials full URI (http://amazonaws.com/full) is specified via a hostname whose IP address(es) do not resolve to the loopback device.")
     }
 
+    @Test
+    fun testLocalFullUri() = runTest {
+        val uri = "http://localhost"
+        val engine = buildTestConnection {
+            expect(
+                ecsRequest(uri),
+                ecsResponse(),
+            )
+        }
+
+        val testPlatform = TestPlatformProvider(
+            env = mapOf(AwsSdkSetting.AwsContainerCredentialsFullUri.envVar to uri),
+        )
+
+        val provider = EcsCredentialsProvider(testPlatform, engine)
+        val actual = provider.resolve()
+        assertEquals(expectedCredentials, actual)
+        engine.assertRequests()
+    }
+
     @Test
     fun testNonexistentFullUri() = runTest {
         val uri = "http://amazonaws.net/full"