fix: ensure output of GraphViewTask is fully sorted (therefore deterministic).

Author: autonomousapps

src/main/kotlin/com/autonomousapps/internal/graph/GraphWriter.kt

@@ -3,23 +3,33 @@
 package com.autonomousapps.internal.graph
 
 import com.autonomousapps.graph.Graphs.root
-import com.autonomousapps.graph.Graphs.shortestPaths
 import com.autonomousapps.graph.Graphs.topological
 import com.autonomousapps.internal.utils.appendReproducibleNewLine
 import com.autonomousapps.model.Coordinates
 import com.autonomousapps.model.ProjectCoordinates
+import com.google.common.graph.EndpointPair
 import com.google.common.graph.Graph
 import com.google.common.graph.Traverser
 
 @Suppress("UnstableApiUsage")
 internal class GraphWriter(private val buildPath: String) {
 
+  private companion object {
+    // TODO(tsr): similar code in moshi.kt
+    val EDGE_COMPARATOR: Comparator<EndpointPair<Coordinates>> = Comparator { left, right ->
+      compareBy(EndpointPair<Coordinates>::source)
+        .thenComparing(EndpointPair<Coordinates>::target)
+        .compare(left, right)
+    }
+  }
+
   fun toDot(graph: Graph<Coordinates>): String = buildString {
     val projectNodes = graph.nodes().asSequence()
       // Maybe transform an IncludedBuildCoordinates into its resolvedProject for more human-readable reporting
       .map { it.maybeProjectCoordinates(buildPath) }
       .filterIsInstance<ProjectCoordinates>()
       .map { it.gav() }
+      .sorted()
       .toList()
 
     appendReproducibleNewLine("strict digraph DependencyGraph {")
@@ -34,15 +44,17 @@ internal class GraphWriter(private val buildPath: String) {
     if (projectNodes.isNotEmpty()) appendReproducibleNewLine()
 
     // the graph itself
-    graph.edges().forEach { edge ->
-      val source = edge.nodeU().maybeProjectCoordinates(buildPath)
-      val target = edge.nodeV().maybeProjectCoordinates(buildPath)
-      val style =
-        if (source is ProjectCoordinates && target is ProjectCoordinates) " [style=bold color=\"#FF6347\" weight=8]"
-        else ""
-      append("  \"${source.gav()}\" -> \"${target.gav()}\"$style;")
-      append("\n")
-    }
+    graph.edges()
+      .sortedWith(EDGE_COMPARATOR)
+      .forEach { edge ->
+        val source = edge.nodeU().maybeProjectCoordinates(buildPath)
+        val target = edge.nodeV().maybeProjectCoordinates(buildPath)
+        val style =
+          if (source is ProjectCoordinates && target is ProjectCoordinates) " [style=bold color=\"#FF6347\" weight=8]"
+          else ""
+        append("  \"${source.gav()}\" -> \"${target.gav()}\"$style;")
+        append("\n")
+      }
     append("}")
   }
 

src/main/kotlin/com/autonomousapps/internal/utils/moshi.kt

@@ -205,10 +205,10 @@ internal class GraphAdapter {
       variant = graphView.variant,
       configurationName = graphView.configurationName,
       graphJson = GraphJson(
-        nodes = graphView.graph.nodes(),
+        nodes = graphView.graph.nodes().toSortedSet(),
         edges = graphView.graph.edges().asSequence().map { pair ->
           pair.nodeU() to pair.nodeV()
-        }.toSet(),
+        }.toSortedSet(),
       ),
     )
   }
@@ -223,10 +223,10 @@ internal class GraphAdapter {
 
   @ToJson fun graphToJson(graph: Graph<Coordinates>): GraphJson {
     return GraphJson(
-      nodes = graph.nodes(),
+      nodes = graph.nodes().toSortedSet(),
       edges = graph.edges().asSequence().map { pair ->
         pair.nodeU() to pair.nodeV()
-      }.toSet(),
+      }.toSortedSet(),
     )
   }
 
@@ -265,5 +265,12 @@ internal class GraphAdapter {
   )
 
   @JsonClass(generateAdapter = false)
-  internal data class EdgeJson(val source: Coordinates, val target: Coordinates)
+  internal data class EdgeJson(val source: Coordinates, val target: Coordinates) : Comparable<EdgeJson> {
+    // TODO(tsr): similar code in GraphWriter
+    override fun compareTo(other: EdgeJson): Int {
+      return compareBy(EdgeJson::source)
+        .thenComparing(EdgeJson::target)
+        .compare(this, other)
+    }
+  }
 }

src/main/kotlin/com/autonomousapps/tasks/GraphViewTask.kt

@@ -153,7 +153,7 @@ abstract class GraphViewTask : DefaultTask() {
 
     output.bufferWriteJson(compileGraphView)
     outputDot.writeText(graphWriter.toDot(compileGraph))
-    outputNodes.bufferWriteJson(CoordinatesContainer(compileGraphView.nodes))
+    outputNodes.bufferWriteJson(CoordinatesContainer(compileGraphView.nodes.toSortedSet()))
     outputRuntime.bufferWriteJson(runtimeGraphView)
     outputRuntimeDot.writeText(graphWriter.toDot(runtimeGraph))
   }

src/test/kotlin/com/autonomousapps/model/internal/DependencyGraphViewTest.kt

@@ -30,7 +30,7 @@ internal class DependencyGraphViewTest {
     val serialized = graphView.toJson()
     assertThat(serialized).isEqualTo(
       """
-        {"variant":{"variant":"main","kind":"MAIN"},"configurationName":"compileClasspath","graphJson":{"nodes":[{"type":"project","identifier":":secondary:root","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},{"type":"project","identifier":":root","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},{"type":"module","identifier":"foo:bar","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},{"type":"module","identifier":"bar:baz","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}}],"edges":[{"source":{"type":"project","identifier":":root","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},"target":{"type":"module","identifier":"foo:bar","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}}},{"source":{"type":"module","identifier":"foo:bar","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},"target":{"type":"module","identifier":"bar:baz","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}}}]}}
+        {"variant":{"variant":"main","kind":"MAIN"},"configurationName":"compileClasspath","graphJson":{"nodes":[{"type":"module","identifier":"bar:baz","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},{"type":"module","identifier":"foo:bar","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},{"type":"project","identifier":":root","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},{"type":"project","identifier":":secondary:root","gradleVariantIdentification":{"capabilities":[],"attributes":{}}}],"edges":[{"source":{"type":"module","identifier":"foo:bar","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},"target":{"type":"module","identifier":"bar:baz","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}}},{"source":{"type":"project","identifier":":root","gradleVariantIdentification":{"capabilities":[],"attributes":{}}},"target":{"type":"module","identifier":"foo:bar","resolvedVersion":"1","gradleVariantIdentification":{"capabilities":[],"attributes":{}}}}]}}
       """.trimIndent()
     )