fix converting introspection to SDL

Author: martinbonnin

apollo-compiler/src/main/kotlin/com/apollographql/apollo/compiler/parser/introspection/introspection2sdl.kt

@@ -137,7 +137,14 @@ private fun IntrospectionSchema.InputField.toSDL(sink: BufferedSink) {
   sink.writeUtf8("  $name: ${type.asGraphQLType()}")
   if (defaultValue != null) {
     sink.writeUtf8(" = ")
-    sink.writeValue(defaultValue)
+    if (defaultValue is String) {
+      // defaultValue is already encoded as GraphQL, we can pass it verbatim
+      sink.writeUtf8(defaultValue)
+    } else {
+      // legacy mode if we bump into an introspection schema that doesn't encode the default value
+      sink.writeValue(defaultValue)
+    }
+
   }
   sink.writeDeprecatedDirective(isDeprecated, deprecationReason)
 }
@@ -177,7 +184,13 @@ private fun IntrospectionSchema.Field.Argument.toSDL(sink: BufferedSink) {
   sink.writeUtf8("$name: ${type.asGraphQLType()}")
   if (defaultValue != null) {
     sink.writeUtf8(" = ")
-    sink.writeValue(defaultValue)
+    if (defaultValue is String) {
+      // defaultValue is already encoded as GraphQL, we can pass it verbatim
+      sink.writeUtf8(defaultValue)
+    } else {
+      // legacy mode if we bump into an introspection schema that doesn't encode the default value
+      sink.writeValue(defaultValue)
+    }
   }
   sink.writeDeprecatedDirective(isDeprecated, deprecationReason)
 }

apollo-compiler/src/test/kotlin/com/apollographql/apollo/compiler/GraphSdlParseTest.kt

@@ -6,7 +6,6 @@ import com.apollographql.apollo.compiler.parser.introspection.IntrospectionSchem
 import com.apollographql.apollo.compiler.parser.introspection.toSDL
 import com.apollographql.apollo.compiler.parser.sdl.GraphSdlSchema
 import com.apollographql.apollo.compiler.parser.sdl.toIntrospectionSchema
-import com.google.common.truth.Truth
 import com.google.common.truth.Truth.assertThat
 import org.junit.Assert.assertEquals
 import org.junit.Assert.fail
@@ -84,6 +83,17 @@ class GraphSdlParseTest() {
     assertEquals(initialSchema, finalSchema)
   }
 
+  @Test
+  fun `defaultValues are correctly written`() {
+    val initialSchema = IntrospectionSchema(File("src/test/sdl/default-values.json")).normalize()
+    val sdlFile = File("build/sdl-test/schema.sdl")
+    sdlFile.parentFile.deleteRecursively()
+    sdlFile.parentFile.mkdirs()
+    initialSchema.toSDL(sdlFile)
+
+    assertEquals(File("src/test/sdl/default-values.sdl").readText(), sdlFile.readText())
+  }
+
   /**
    * use to make easier diffs
    */