improve error messages (#73)

src/main/kotlin/com/parmet/buf/gradle/Breaking.kt

@@ -62,6 +62,11 @@ private fun Project.configureBreakingTask() {
             bufBuildPublicationFile,
             "--against",
             singleFileFromConfiguration(BUF_BREAKING_CONFIGURATION_NAME)
-        )
+        ) {
+            """
+                |Some Protobuf files had breaking changes:
+                |$it
+            """.trimMargin()
+        }
     }
 }

src/main/kotlin/com/parmet/buf/gradle/BufSupport.kt

@@ -19,6 +19,8 @@ import org.gradle.api.Project
 import org.gradle.api.Task
 import org.gradle.kotlin.dsl.ivy
 import org.gradle.kotlin.dsl.repositories
+import java.io.ByteArrayOutputStream
+import java.nio.charset.StandardCharsets
 
 const val BUF_BINARY_CONFIGURATION_NAME = "bufTool"
 
@@ -54,17 +56,19 @@ internal fun Project.configureBufDependency() {
     )
 }
 
-internal fun Task.execBuf(vararg args: Any) {
-    execBuf(args.asList())
+internal fun Task.execBuf(vararg args: Any, customErrorMessage: ((String) -> String)? = null) {
+    execBuf(args.asList(), customErrorMessage)
 }
 
-internal fun Task.execBuf(args: Iterable<Any>) {
+internal fun Task.execBuf(args: Iterable<Any>, customErrorMessage: ((String) -> String)? = null) {
     if (project.hasProtobufGradlePlugin()) {
         dependsOn(CREATE_SYM_LINKS_TO_MODULES_TASK_NAME)
         dependsOn(WRITE_WORKSPACE_YAML_TASK_NAME)
     }
     doLast {
         with(project) {
+            val out = ByteArrayOutputStream()
+
             exec {
                 val executable = singleFileFromConfiguration(BUF_BINARY_CONFIGURATION_NAME)
 
@@ -82,8 +86,23 @@ internal fun Task.execBuf(args: Iterable<Any>) {
 
                 commandLine(executable)
                 setArgs(args)
+                isIgnoreExitValue = true
+
+                if (customErrorMessage != null) {
+                    standardOutput = out
+                }
 
                 logger.info("Running buf from $workingDir: `buf ${args.joinToString(" ")}`")
+            }.also {
+                if (customErrorMessage == null) {
+                    it.assertNormalExitValue()
+                } else {
+                    if (it.exitValue != 0) {
+                        throw IllegalStateException(
+                            customErrorMessage(out.toByteArray().toString(StandardCharsets.UTF_8))
+                        )
+                    }
+                }
             }
         }
     }

src/main/kotlin/com/parmet/buf/gradle/DirectorySpecificBufExecutionSupport.kt

@@ -19,31 +19,34 @@ import org.gradle.api.Task
 import java.nio.file.Path
 
 internal fun Task.configureDirectorySpecificBufExecution(
-    vararg bufCommand: String
+    vararg bufCommand: String,
+    customErrorMessage: ((String) -> String)? = null
 ) {
-    configureDirectorySpecificBufExecution(bufCommand.asList(), emptyList())
+    configureDirectorySpecificBufExecution(bufCommand.asList(), emptyList(), customErrorMessage)
 }
 
 internal fun Task.configureDirectorySpecificBufExecution(
     bufCommand: String,
-    extraArgs: Iterable<String>
+    extraArgs: Iterable<String>,
+    customErrorMessage: ((String) -> String)
 ) {
-    configureDirectorySpecificBufExecution(listOf(bufCommand), extraArgs)
+    configureDirectorySpecificBufExecution(listOf(bufCommand), extraArgs, customErrorMessage)
 }
 
 private fun Task.configureDirectorySpecificBufExecution(
     bufCommand: Iterable<String>,
-    extraArgs: Iterable<String>
+    extraArgs: Iterable<String>,
+    customErrorMessage: ((String) -> String)? = null
 ) {
-    fun lintWithArgs(path: Path? = null) =
+    fun runWithArgs(path: Path? = null) =
         bufCommand + listOfNotNull(path?.let(::mangle)) + extraArgs
 
     when {
         project.hasProtobufGradlePlugin() ->
-            project.srcProtoDirs().forEach { execBuf(lintWithArgs(it)) }
+            project.srcProtoDirs().forEach { execBuf(runWithArgs(it), customErrorMessage) }
         project.hasWorkspace() ->
-            execBuf(bufCommand)
+            execBuf(bufCommand, customErrorMessage)
         else ->
-            execBuf(lintWithArgs())
+            execBuf(runWithArgs(), customErrorMessage)
     }
 }

src/main/kotlin/com/parmet/buf/gradle/Format.kt

@@ -33,7 +33,13 @@ private fun Project.configureBufFormatCheck() {
         description = "Checks that a Protobuf schema is formatted according to Buf's formatting rules."
         enabled = getExtension().enforceFormat
 
-        configureDirectorySpecificBufExecution("format", "-d", "--exit-code")
+        configureDirectorySpecificBufExecution("format", "-d", "--exit-code") {
+            """
+                 |Some Protobuf files had format violations:
+                 |$it
+                 |Run './gradlew :bufFormatApply' to fix these violations.
+            """.trimMargin()
+        }
     }
 
     tasks.named(CHECK_TASK_NAME).dependsOn(BUF_FORMAT_CHECK_TASK_NAME)

src/main/kotlin/com/parmet/buf/gradle/Lint.kt

@@ -29,7 +29,12 @@ internal fun Project.configureLint() {
         configureDirectorySpecificBufExecution(
             "lint",
             bufConfigFile()?.let { listOf("--config", it.readText()) }.orEmpty()
-        )
+        ) {
+            """
+                 |Some Protobuf files had lint violations:
+                 |$it
+            """.trimMargin()
+        }
     }
 
     tasks.named(CHECK_TASK_NAME).dependsOn(BUF_LINT_TASK_NAME)

src/test/kotlin/com/parmet/buf/gradle/AbstractBreakingTest.kt

@@ -58,6 +58,12 @@ abstract class AbstractBreakingTest : AbstractBufIntegrationTest() {
 
         val result = checkRunner().buildAndFail()
         assertThat(result.task(":$BUF_BREAKING_TASK_NAME")?.outcome).isEqualTo(FAILED)
+        assertThat(result.output).contains(
+            """
+                Execution failed for task ':bufBreaking'.
+                > Some Protobuf files had breaking changes:
+            """.trimIndent()
+        )
         assertThat(result.output).contains("Previously present message \"BasicMessage\" was deleted from file.")
     }
 

src/test/kotlin/com/parmet/buf/gradle/AbstractFormatCheckTest.kt

@@ -29,33 +29,32 @@ abstract class AbstractFormatCheckTest : AbstractBufIntegrationTest() {
 
     @Test
     fun `format an incorrect message`() {
-        baseAssertBadWhitespace()
+        assertBadWhitespace()
     }
 
     @Test
     fun `do not format an incorrect message when enforcement is disabled`() {
-        baseAssertBadWhitespace()
+        assertBadWhitespace()
 
         buildFile.replace("enforceFormat = true", "enforceFormat = false")
 
         assertSuccess()
     }
 
-    private fun baseAssertBadWhitespace() {
-        assertBadWhitespace(
-            """
-                -message Foo {
-                -
-                -}
-                +message Foo {}
-            """.trimIndent()
-        )
-    }
-
-    protected fun assertBadWhitespace(diff: String) {
+    protected fun assertBadWhitespace() {
         val result = checkRunner().buildAndFail()
         assertThat(result.task(":$BUF_FORMAT_CHECK_TASK_NAME")?.outcome).isEqualTo(FAILED)
-        assertThat(result.output).contains(diff)
+        assertThat(result.output)
+            .contains(
+                """
+                    |  -message Foo {
+                    |  -
+                    |  -}
+                    |  +message Foo {}
+                    |  
+                    |  Run './gradlew :bufFormatApply' to fix these violations.
+                """.trimMargin()
+            )
     }
 
     protected fun assertSuccess() {

src/test/kotlin/com/parmet/buf/gradle/AbstractLintTest.kt

@@ -40,6 +40,12 @@ abstract class AbstractLintTest : LintTestUtilities, AbstractBufIntegrationTest(
     private fun assertBadEnumSuffix() {
         val result = checkRunner().buildAndFail()
         assertThat(result.task(":$BUF_LINT_TASK_NAME")?.outcome).isEqualTo(FAILED)
+        assertThat(result.output).contains(
+            """
+                Execution failed for task ':bufLint'.
+                > Some Protobuf files had lint violations:
+            """.trimIndent()
+        )
         assertThat(result.output).contains("Enum zero value name \"TEST_FOO\" should be suffixed with \"_UNSPECIFIED\"")
     }
 }

src/test/kotlin/com/parmet/buf/gradle/FormatCheckWithProtobufGradleTest.kt

@@ -35,15 +35,7 @@ class FormatCheckWithProtobufGradleTest : AbstractFormatCheckTest() {
 
     @Test
     fun `format a bad separate protobuf source directory through the protobuf-gradle-plugin`() {
-        assertBadWhitespace(
-            """
-                -message BasicMessage {
-                -
-                -
-                -}
-                +message BasicMessage {}
-            """.trimIndent()
-        )
+        assertBadWhitespace()
     }
 
     @Test
@@ -53,15 +45,6 @@ class FormatCheckWithProtobufGradleTest : AbstractFormatCheckTest() {
 
     @Test
     fun `format a bad file with a protobuf dependency and a google dependency with the protobuf-gradle-plugin`() {
-        assertBadWhitespace(
-            """
-                 message BasicMessage {
-                -
-                -
-                   google.protobuf.Any any = 1;
-                   protokt.ProtoktFileOptions protokt_file_options = 2;
-                 }
-            """.trimIndent()
-        )
+        assertBadWhitespace()
     }
 }

src/test/resources/FormatCheckWithProtobufGradleTest/format a bad file with a protobuf dependency and a google dependency with the protobuf-gradle-plugin/src/main/proto/parmet/buf/test/v1/test.proto

@@ -19,8 +19,10 @@ import "google/protobuf/any.proto";
 import "protokt/protokt.proto";
 
 message BasicMessage {
-
-
   google.protobuf.Any any = 1;
   protokt.ProtoktFileOptions protokt_file_options = 2;
 }
+
+message Foo {
+
+}

src/test/resources/FormatCheckWithProtobufGradleTest/format a bad separate protobuf source directory through the protobuf-gradle-plugin/subdir/parmet/buf/test/v1/test.proto

@@ -15,7 +15,6 @@ syntax = "proto3";
 
 package parmet.buf.test.v1;
 
-message BasicMessage {
-
+message Foo {
 
 }