message: Only write the header warning once per file
diff: @@ -7,6 +7,7 @@ package software.amazon.smithy.rust.lang
  import io.kotest.matchers.collections.shouldContain
  import io.kotest.matchers.string.shouldContain
  +import io.kotest.matchers.string.shouldContainOnlyOnce
  import org.junit.jupiter.api.Test
  import software.amazon.smithy.codegen.core.SymbolProvider
  import software.amazon.smithy.model.Model
  @@ -34,7 +35,7 @@ class RustWriterTest {
  @Test
  fun `inner modules correctly handle dependencies`() {
  - val sut = RustWriter.forModule("lib")
  + val sut = RustWriter.forModule("parent")
  val requestBuilder = RuntimeType.HttpRequestBuilder
  sut.withModule("inner") {
  rustBlock("fn build(builer: \$T)", requestBuilder) {
  @@ -42,6 +43,7 @@ class RustWriterTest {
  }
  val httpDep = CargoDependency.Http.dependencies[0]
  sut.dependencies shouldContain httpDep
  + sut.toString() shouldContainOnlyOnce "DO NOT EDIT"
  }
  @Test
  