add dev mode where warnings don't fail the test

.gitignore

@@ -11,6 +11,7 @@ target
 **/build/
 **/generated/
 examples/**/build/
+build-cache/
 
 # Eclipse #
 ###########

conventions/src/main/kotlin/otel.java-conventions.gradle.kts

@@ -72,12 +72,13 @@ tasks.withType<JavaCompile>().configureEach {
           // We suppress the "options" warning because it prevents compilation on modern JDKs
           "-Xlint:-options",
           // jdk21 generates more serial warnings than previous versions
-          "-Xlint:-serial",
-
-          // Fail build on any warning
-          "-Werror"
+          "-Xlint:-serial"
         )
       )
+      if (System.getProperty("dev") != "true") {
+        // Fail build on any warning
+        compilerArgs.add("-Werror")
+      }
     }
 
     encoding = "UTF-8"

docs/contributing/running-tests.md

@@ -38,6 +38,23 @@ To run these tests locally, add `-PtestLatestDeps=true` to your existing `gradle
 
 Executing `./gradlew :instrumentation:<INSTRUMENTATION_NAME>:test --tests <GROOVY TEST FILE NAME>` will run only the selected test.
 
+### Ignoring warnings in tests
+
+During local development, you may want to ignore warnings in tests.
+
+To ignore warnings, formatting issues, or other non-fatal issues in tests, use
+
+```
+./gradlew test -Ddev=true -x spotlessCheck -x checkstyleMain
+```
+
+The `dev` flag
+
+- will ignore warnings in tests
+- will use a local build cache, which can speed up the build
+
+The local build cache is also useful for other commands, such as `./gradlew spotlessApply -Ddev=true`.
+
 ## Smoke tests
 
 The smoke tests are not run as part of a global `test` task run since they take a long time and are

settings.gradle.kts

@@ -81,8 +81,15 @@ if (useScansGradleCom) {
   }
 
   buildCache {
-    remote(develocity.buildCache) {
-      isPush = isCI && geAccessKey.isNotEmpty()
+    if (System.getProperty("dev") == "true") {
+      local {
+        directory = File(rootDir, "build-cache")
+        removeUnusedEntriesAfterDays = 30
+      }
+    } else {
+      remote(develocity.buildCache) {
+        isPush = isCI && geAccessKey.isNotEmpty()
+      }
     }
   }
 }