Track API changes in CI

using Metalava.

1 files changed, 77 insertions, 0 deletions

diff --git a/buildSrc/src/main/kotlin/com/google/devtools/ksp/ApiCheck.kt b/buildSrc/src/main/kotlin/com/google/devtools/ksp/ApiCheck.kt
new file mode 100644
index 00000000..ddd04a29
--- /dev/null
+++ b/buildSrc/src/main/kotlin/com/google/devtools/ksp/ApiCheck.kt
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2022 Google LLC
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.devtools.ksp
+
+import org.gradle.api.Project
+import org.gradle.api.artifacts.Configuration
+import org.gradle.api.tasks.JavaExec
+
+val API_BASE_FILE="api.base"
+
+/**
+ * Adapted from ktlint
+ */
+fun Project.configureMetalava() {
+    val checkProvider = tasks.register("checkApi", JavaExec::class.java) { task ->
+        task.configureCommonMetalavaArgs(this@configureMetalava)
+        task.description = "Check API compatibility."
+        task.group = "Verification"
+        task.args = listOf("--check-compatibility:api:released", API_BASE_FILE) + task.args!!
+    }
+
+    afterEvaluate {
+        // check task is not available yet, which is why we use afterEvaluate
+        project.tasks.named("check").configure { checkTask ->
+            checkTask.dependsOn(checkProvider)
+        }
+    }
+
+    tasks.register("updateApi", JavaExec::class.java) { task ->
+        task.configureCommonMetalavaArgs(this@configureMetalava)
+        task.description = "Update API base file."
+        task.group = "formatting"
+        task.args = listOf("--api", API_BASE_FILE) + task.args!!
+    }
+}
+
+/**
+ * Configures common Metalava parameters
+ */
+private fun JavaExec.configureCommonMetalavaArgs(
+    project: Project
+) {
+    val apiFiles = project.fileTree(project.projectDir).also {
+        it.include("**/*.kt")
+        it.include("**/*.java")
+        it.exclude("**/testData/**")
+        it.exclude("**/build/**")
+        it.exclude("**/.*/**")
+    }
+    inputs.files(apiFiles)
+    classpath = project.getMetalavaConfiguration()
+    main = "com.android.tools.metalava.Driver"
+    args = listOf(
+        "--source-files",
+    ) + apiFiles.files.map { it.absolutePath }
+}
+
+private fun Project.getMetalavaConfiguration(): Configuration {
+    return configurations.findByName("metalava") ?: configurations.create("metalava") {
+        val dependency = dependencies.create("com.android.tools.metalava:metalava:1.0.0-alpha04")
+        it.dependencies.add(dependency)
+    }
+}