test(backend): add failing tests for step 1 — llama env-only config

backend/src/test/kotlin/com/condado/newsletter/service/LlamaConfigurationBindingTest.kt

@@ -0,0 +1,30 @@
+package com.condado.newsletter.service
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.springframework.beans.factory.annotation.Value
+import java.nio.file.Files
+import java.nio.file.Path
+
+class LlamaConfigurationBindingTest {
+
+    @Test
+    fun should_bindLlamaBaseUrlAndModelWithoutFallback_when_readingServiceValueAnnotations() {
+        val constructor = LlamaPreviewService::class.java.declaredConstructors.single()
+        val baseUrlExpression = constructor.parameters[1].getAnnotation(Value::class.java).value
+        val modelExpression = constructor.parameters[2].getAnnotation(Value::class.java).value
+
+        assertThat(baseUrlExpression).isEqualTo("\${llama.base-url}")
+        assertThat(modelExpression).isEqualTo("\${llama.model}")
+    }
+
+    @Test
+    fun should_referenceEnvironmentPlaceholdersWithoutFallback_when_readingApplicationYaml() {
+        val yaml = Files.readString(Path.of("src/main/resources/application.yml"))
+
+        assertThat(yaml).contains("base-url: \${LLAMA_BASE_URL}")
+        assertThat(yaml).contains("model: \${LLAMA_MODEL}")
+        assertThat(yaml).doesNotContain("LLAMA_BASE_URL:http://localhost:11434")
+        assertThat(yaml).doesNotContain("LLAMA_MODEL:gemma3:4b")
+    }
+}