Merge pull request #419 from Netflix/feature/codegen-syntax-insight

Author: berngp

graphql-dgs-codegen-core/src/main/kotlin/com/netflix/graphql/dgs/codegen/CodeGen.kt

@@ -34,10 +34,12 @@ import com.netflix.graphql.dgs.codegen.generators.shared.excludeSchemaTypeExtens
 import com.squareup.javapoet.JavaFile
 import com.squareup.kotlinpoet.FileSpec
 import graphql.language.*
+import graphql.parser.InvalidSyntaxException
 import graphql.parser.MultiSourceReader
 import graphql.parser.Parser
 import graphql.parser.ParserOptions
 import java.io.File
+import java.io.Reader
 import java.nio.file.Path
 import java.nio.file.Paths
 
@@ -97,28 +99,41 @@ class CodeGen(private val config: CodeGenConfig) {
             builder.maxTokens(SDL_MAX_ALLOWED_SCHEMA_TOKENS)
         }
         val parser = Parser()
-        val readerBuilder = MultiSourceReader.newMultiSourceReader()
-
-        val schemaFiles = config.schemaFiles.sorted()
-            .flatMap { it.walkTopDown() }
-            .filter { it.isFile }
 
-        for (schemaFile in schemaFiles) {
-            schemaFile.appendText("\n")
-            readerBuilder.reader(schemaFile.reader(), schemaFile.name)
-        }
-
-        for (schema in config.schemas) {
-            readerBuilder.string(schema, null)
-        }
+        val readerBuilder = MultiSourceReader.newMultiSourceReader()
+        val debugReaderBuilder = MultiSourceReader.newMultiSourceReader()
 
+        loadSchemaReaders(readerBuilder, debugReaderBuilder)
         val document = readerBuilder.build().use { reader ->
-            parser.parseDocument(reader, options)
+            try {
+                parser.parseDocument(reader, options)
+            } catch (exception: InvalidSyntaxException) {
+                throw CodeGenSchemaParsingException(debugReaderBuilder.build(), exception)
+            }
         }
 
         return document
     }
 
+    /**
+     * Loads the given [MultiSourceReader.Builder] references with the sources that will be used to provide
+     * the schema information for the parser.
+     */
+    private fun loadSchemaReaders(vararg readerBuilders: MultiSourceReader.Builder) {
+        readerBuilders.forEach { rb ->
+            val schemaFiles = config.schemaFiles.sorted()
+                .flatMap { it.walkTopDown() }
+                .filter { it.isFile }
+            for (schemaFile in schemaFiles) {
+                rb.string("\n", "codegen")
+                rb.reader(schemaFile.reader(), schemaFile.name)
+            }
+            for (schema in config.schemas) {
+                rb.string(schema, null)
+            }
+        }
+    }
+
     private fun generateJava(): CodeGenResult {
         val definitions = document.definitions
         // data types
@@ -618,3 +633,30 @@ fun Type<*>.findBaseTypeDefinition(): TypeDefinition<*>? {
         }
     }
 }
+
+class CodeGenSchemaParsingException(
+    schemaReader: Reader,
+    invalidSyntaxException: InvalidSyntaxException
+) : RuntimeException(buildMessage(schemaReader, invalidSyntaxException), invalidSyntaxException) {
+    companion object {
+        private fun buildMessage(
+            schemaReader: Reader,
+            invalidSyntaxException: InvalidSyntaxException
+        ): String {
+            schemaReader.use { reader ->
+                return """
+                |Unable to parse the schema...
+                |${invalidSyntaxException.message}
+                | 
+                |Schema Section:
+                |>>>
+                |${invalidSyntaxException.sourcePreview}
+                |<<<
+                |
+                |Full Schema:
+                |${reader.readText()}
+                """.trimMargin()
+            }
+        }
+    }
+}

graphql-dgs-codegen-core/src/test/kotlin/com/netflix/graphql/dgs/codegen/CodeGenTest.kt

@@ -23,6 +23,7 @@ import com.squareup.javapoet.ClassName
 import com.squareup.javapoet.JavaFile
 import com.squareup.javapoet.ParameterizedTypeName
 import com.squareup.javapoet.WildcardTypeName
+import org.assertj.core.api.Assertions
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
@@ -36,6 +37,46 @@ import java.util.stream.Stream
 
 class CodeGenTest {
 
+    @Test
+    fun `When the schema fails to parse, is able to print the error message along with the schema`() {
+        val schema = """
+            type Query {
+                people: [Person]
+            }
+            type Person {
+                firstname: String
+                lastname: String
+            }
+            type Mutation {
+        """.trimIndent()
+
+        Assertions.assertThatThrownBy {
+            CodeGen(CodeGenConfig(schemas = setOf(schema), packageName = basePackageName)).generate()
+        }.isInstanceOf(CodeGenSchemaParsingException::class.java)
+            .hasMessageContainingAll(
+                "Invalid Syntax : offending token '<EOF>' at line 8 column 16",
+                """
+                |Schema Section:
+                |>>>
+                |    firstname: String
+                |    lastname: String
+                |}
+                |type Mutation {
+                |
+                """.trimMargin(),
+                """Full Schema:
+                |type Query {
+                |    people: [Person]
+                |}
+                |type Person {
+                |    firstname: String
+                |    lastname: String
+                |}
+                |type Mutation {
+                """.trimMargin()
+            )
+    }
+
     @Test
     fun generateDataClassWithStringProperties() {
         val schema = """