Initial XML diff

Author: stringbean

xml-compare/src/main/scala/software/purpledragon/xml/compare/XmlCompare.scala

@@ -0,0 +1,37 @@
+package software.purpledragon.xml.compare
+
+import software.purpledragon.xml.compare.options.DiffOption._
+import software.purpledragon.xml.compare.options.DiffOptions
+
+import scala.xml.Node
+
+object XmlCompare {
+  private type Check = (Node, Node, DiffOptions) => XmlDiff
+
+  val DefaultOptions: DiffOptions = Set(IgnorePrefix)
+
+  def compare(left: Node, right: Node, options: DiffOptions = DefaultOptions): XmlDiff = {
+    val checks: Seq[Check] = Seq(compareNamespace)
+
+    checks.foldLeft[XmlDiff](XmlEqual) { (status, check) =>
+      if (!status.isEqual) {
+        // already failed
+        status
+      } else {
+        check(left, right, options)
+      }
+    }
+  }
+
+  private def compareNamespace(left: Node, right: Node, options: DiffOptions): XmlDiff = {
+    if (left.label != right.label) {
+      XmlDiffers("different label")
+    } else if (left.namespace != right.namespace) {
+      XmlDiffers("different namespace")
+    } else if (left.prefix != right.prefix && !options.contains(IgnorePrefix)) {
+      XmlDiffers("different prefix")
+    } else {
+      XmlEqual
+    }
+  }
+}

xml-compare/src/main/scala/software/purpledragon/xml/compare/XmlDiff.scala

@@ -0,0 +1,13 @@
+package software.purpledragon.xml.compare
+
+sealed trait XmlDiff {
+  def isEqual: Boolean
+}
+
+object XmlEqual extends XmlDiff {
+  override def isEqual: Boolean = true
+}
+
+case class XmlDiffers(reason: String) extends XmlDiff {
+  override def isEqual: Boolean = false
+}

xml-compare/src/main/scala/software/purpledragon/xml/compare/options/DiffOption.scala

@@ -0,0 +1,7 @@
+package software.purpledragon.xml.compare.options
+
+object DiffOption extends Enumeration {
+  type DiffOption = Value
+
+  val IgnorePrefix = DiffOption
+}

xml-compare/src/main/scala/software/purpledragon/xml/compare/options/package.scala

@@ -0,0 +1,5 @@
+package software.purpledragon.xml.compare
+
+package object options {
+  type DiffOptions = Set[DiffOption.type]
+}

xml-compare/src/test/scala/software/purpledragon/xml/compare/XmlCompareSpec.scala

@@ -0,0 +1,40 @@
+package software.purpledragon.xml.compare
+
+import org.scalatest.{FlatSpec, Matchers}
+
+class XmlCompareSpec extends FlatSpec with Matchers {
+
+  "comparing empty" should "match same element name" in {
+    XmlCompare.compare(<test/>, <test/>) shouldBe XmlEqual
+  }
+
+  it should "blah" in {
+    XmlCompare.compare(<test/>, <test></test>) shouldBe XmlEqual
+  }
+
+  it should "not-match" in {
+    XmlCompare.compare(<test/>, <foo/>) shouldBe XmlDiffers("different label")
+  }
+
+  it should "match same namespaces" in {
+    XmlCompare.compare(<t:test xmlns:t="http://example.com"/>, <t:test xmlns:t="http://example.com"/>) shouldBe XmlEqual
+  }
+
+  it should "match different namespace prefix" in {
+    XmlCompare.compare(
+        <t:test xmlns:t="http://example.com"/>,
+        <e:test xmlns:e="http://example.com"/>) shouldBe XmlEqual
+  }
+
+  it should "not-match different namespace prefix (with IgnorePrefix disabled)" in {
+    XmlCompare.compare(
+        <t:test xmlns:t="http://example.com"/>,
+        <e:test xmlns:e="http://example.com"/>, Set.empty) shouldBe XmlDiffers("different prefix")
+  }
+
+  it should "not-match different namespace url" in {
+    XmlCompare.compare(
+        <t:test xmlns:t="http://example.com"/>,
+        <t:test xmlns:t="http://foo.com"/>) shouldBe XmlDiffers("different namespace")
+  }
+}