Add PomFilter to filter out "scoverage" and "silencer"

Motivation:

- "provided" does not remove dependencies from a pom.xml
- use a snippet from typelevel#739 to exclude undesired dependencies
- apply PomFilter to exlude scoverage too.

build.sbt

@@ -124,22 +124,14 @@ val commonSettings = Seq(
          |limitations under the License.""".stripMargin
     )
   ),
-  // For evicting Scoverage out of the generated POM
-  // See: https://github.com/scoverage/sbt-scoverage/issues/153
-  pomPostProcess := { (node: xml.Node) =>
-    new RuleTransformer(new RewriteRule {
-      override def transform(node: xml.Node): Seq[xml.Node] = node match {
-        case e: Elem
-            if e.label == "dependency" && e.child
-              .exists(child => child.label == "groupId" && child.text == "org.scoverage") =>
-          Nil
-        case _ => Seq(node)
-      }
-    }).transform(node).head
-  },
   addCompilerPlugin(("org.typelevel" %% "kind-projector" % "0.11.0").cross(CrossVersion.full)),
   mimaFailOnNoPrevious := false
-)
+) ++
+  // For evicting Scoverage out of the generated POM
+  // See: https://github.com/scoverage/sbt-scoverage/issues/153
+  PomFilter.filterOutDependencyFromGeneratedPomXml("groupId" -> "org\\.scoverage".r) ++
+  PomFilter.filterOutDependencyFromGeneratedPomXml("groupId" -> "com\\.github\\.ghik".r,
+                                                   "artifactId" -> "silencer-lib".r)
 
 val mimaSettings = Seq(
   mimaPreviousArtifacts := {

project/PomFilter.scala

@@ -0,0 +1,41 @@
+import scala.util.matching.Regex
+import scala.xml.Elem
+import scala.xml.transform.{RewriteRule, RuleTransformer}
+import sbt.Keys.pomPostProcess
+
+object PomFilter {
+  /**
+   * Filter out dependencies from the generated `pom.xml`.
+   *
+   * E.g. to exclude Scoverage:
+   * {{{
+   *   filterOutDependencyFromGeneratedPomXml("groupId" -> "org\\.scoverage".r)
+   * }}}
+   *
+   * Or to exclude based on both `groupId` and `artifactId`:
+   * {{{
+   *   filterOutDependencyFromGeneratedPomXml("groupId" -> "io\\.estatico".r, "artifactId" -> "newtype".r)
+   * }}}
+   */
+  def filterOutDependencyFromGeneratedPomXml(conditions: (String, Regex)*) = {
+    def shouldExclude(e: Elem) =
+      e.label == "dependency" && {
+        conditions.forall { case (key, regex) =>
+          e.child.exists(child => child.label == key && regex.findFirstIn(child.text).isDefined)
+        }
+      }
+
+    if (conditions.isEmpty) Nil else {
+      Seq(
+        pomPostProcess := { (node: xml.Node) =>
+          new RuleTransformer(new RewriteRule {
+            override def transform(node: xml.Node): Seq[xml.Node] = node match {
+              case e: Elem if shouldExclude(e) => Nil
+              case _ => Seq(node)
+            }
+          }).transform(node).head
+        },
+      )
+    }
+  }
+}