Improve the exceptions that are thrown by Kotlin-Guiced

Author: JLLeitschuh

core/src/main/kotlin/org/jlleitschuh/guice/Module.kt

@@ -1,14 +1,18 @@
 package org.jlleitschuh.guice
 
+import com.google.inject.Binder
 import com.google.inject.Module
 import com.google.inject.PrivateModule
+import com.google.inject.binder.AnnotatedBindingBuilder
+import org.jlleitschuh.guice.binder.LinkedBindingBuilderScope
+import org.jlleitschuh.guice.binder.ScopedBindingBuilderScope
 
 /**
  * Creates a [Module] with the [BinderScope] being configured when [Module.configure]
  * is called by Guice.
  */
 fun module(configure: BinderScope.() -> Unit) =
-    Module { binder -> BinderScope(binder).configure() }
+    Module { binder -> BinderScope(binder.excludesLibrarySources()).configure() }
 
 /**
  * Creates a [PrivateModule] with the [PrivateBinderScope] being configured when [PrivateModule.configure]
@@ -18,6 +22,14 @@ fun privateModule(configure: PrivateBinderScope.() -> Unit) =
     // The PrivateModule data type has some reflection checks to get the right type passed in. Easier to just use it.
     object : PrivateModule() {
         override fun configure() =
-            configure.invoke(PrivateBinderScope(binder()))
+            configure.invoke(PrivateBinderScope(binder().excludesLibrarySources()))
+    }
 
-    }
+private inline fun <reified T : Binder> T.excludesLibrarySources(): T =
+    skipSources(
+        BinderScope::class.java,
+        PrivateBinderScope::class.java,
+        AnnotatedBindingBuilder::class.java,
+        LinkedBindingBuilderScope::class.java,
+        ScopedBindingBuilderScope::class.java
+    ) as T

core/src/test/kotlin/org/jlleitschuh/guice/ModuleTest.kt

@@ -1,11 +1,16 @@
 package org.jlleitschuh.guice
 
 import com.google.inject.AbstractModule
+import com.google.inject.CreationException
 import com.google.inject.Guice
+import com.natpryce.hamkrest.and
+import com.natpryce.hamkrest.assertion.assertThat
+import com.natpryce.hamkrest.containsSubstring
 import org.junit.jupiter.api.Assertions.assertNotSame
 import org.junit.jupiter.api.Assertions.assertSame
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
 
 class ModuleTest {
 
@@ -72,4 +77,22 @@ class ModuleTest {
         val second = injector.getInstance(key<Interface>())
         assertNotSame(first, second)
     }
+
+    @Test
+    fun `module binding exceptions provide meaningful exceptions`() {
+        val module = module {
+            bind<Interface>().toProvider<InterfaceProvider>()
+            bind<Interface>().toProvider<InterfaceProvider2>()
+        }
+        val exception = assertThrows<CreationException> {
+            Guice.createInjector(module)
+        }
+
+        val expectedString1 =
+            "1) A binding to org.jlleitschuh.guice.Interface was already configured at org.jlleitschuh.guice.ModuleTest${'$'}module binding exceptions provide meaningful exceptions${'$'}module${'$'}1.invoke(ModuleTest.kt:"
+        val expectedString2 =
+            "at org.jlleitschuh.guice.ModuleTest${'$'}module binding exceptions provide meaningful exceptions${'$'}module${'$'}1.invoke(ModuleTest.kt:"
+
+        assertThat(exception.message!!, containsSubstring(expectedString1) and containsSubstring(expectedString2))
+    }
 }

core/src/test/kotlin/org/jlleitschuh/guice/TestUtility.kt

@@ -9,3 +9,7 @@ class Implementation : Interface
 class InterfaceProvider : Provider<Interface> {
     override fun get() = Implementation()
 }
+
+class InterfaceProvider2 : Provider<Interface> {
+    override fun get() = Implementation()
+}

kotlin-guiced.gradle.kts

@@ -3,6 +3,7 @@ import org.gradle.api.tasks.bundling.Jar
 import org.gradle.api.tasks.testing.logging.TestExceptionFormat
 import org.gradle.api.tasks.testing.logging.TestLogEvent
 import org.gradle.api.tasks.wrapper.Wrapper
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 buildscript {
     repositories {
@@ -69,10 +70,26 @@ subprojects {
 
         "testCompile"(junitJupiter("junit-jupiter-api"))
         "testCompile"(junitJupiter("junit-jupiter-params"))
+        "testCompile"(group = "com.natpryce", name = "hamkrest", version = "1.5.0.0")
         "testRuntime"(junitJupiter("junit-jupiter-engine"))
         "testRuntime"(create(group = "org.junit.platform", name = "junit-platform-launcher", version = "1.3.1"))
     }
 
+    tasks.withType<KotlinCompile>().configureEach {
+        // Kotlin incremental compilation is enabled by default
+        kotlinOptions {
+            jvmTarget = "1.8"
+
+            freeCompilerArgs += "-Xprogressive"
+
+            /*
+             * Enables strict null checking when calling java methods using jsr305 annotations.
+             * https://kotlinlang.org/docs/reference/java-interop.html#jsr-305-support
+             */
+            freeCompilerArgs += "-Xjsr305=strict"
+        }
+    }
+
     tasks.withType<Test>().configureEach {
         extensions.configure(typeOf<JacocoTaskExtension>()) {
             /*