Enclose missing Rust template parameters in backticks in the exception message (#1492)

* Enclose missing Rust template parameters in backticks in the exception message

* appease ktlint

* ./gradlew ktlintFormat

Author: david-perez

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/rustlang/RustWriter.kt

@@ -167,9 +167,10 @@ private fun transformTemplate(template: String, scope: Array<out Pair<String, An
         val templateType = matchResult.groupValues[2].ifEmpty { ":T" }
         if (!scope.toMap().keys.contains(keyName)) {
             throw CodegenException(
-                "Rust block template expected `$keyName` but was not present in template.\n  hint: Template contains: ${
-                    scope.map { it.first }
-                }",
+                """
+                Rust block template expected `$keyName` but was not present in template.
+                Hint: Template contains: ${scope.map { "`${it.first}`" }}
+                """.trimIndent(),
             )
         }
         "#{${keyName.lowercase()}$templateType}"

codegen-core/src/test/kotlin/software/amazon/smithy/rust/codegen/core/rustlang/RustWriterTest.kt

@@ -10,6 +10,8 @@ import io.kotest.matchers.shouldBe
 import io.kotest.matchers.string.shouldContain
 import io.kotest.matchers.string.shouldContainOnlyOnce
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import software.amazon.smithy.codegen.core.CodegenException
 import software.amazon.smithy.model.Model
 import software.amazon.smithy.model.shapes.SetShape
 import software.amazon.smithy.model.shapes.StringShape
@@ -161,6 +163,23 @@ class RustWriterTest {
         sut.toString().shouldContain("inner: hello, regular: http::foo")
     }
 
+    @Test
+    fun `missing template parameters are enclosed in backticks in the exception message`() {
+        val sut = RustWriter.forModule("lib")
+        val exception = assertThrows<CodegenException> {
+            sut.rustTemplate(
+                "#{Foo} #{Bar}",
+                "Foo Bar" to CargoDependency.Http.toType().resolve("foo"),
+                "Baz" to CargoDependency.Http.toType().resolve("foo"),
+            )
+        }
+        exception.message shouldBe
+            """
+            Rust block template expected `Foo` but was not present in template.
+            Hint: Template contains: [`Foo Bar`, `Baz`]
+            """.trimIndent()
+    }
+
     @Test
     fun `can handle file paths properly when determining module`() {
         val sut = RustWriter.forModule("src/module_name")