Handle pre-release qualifiers in version ordering

versions/shared/src/coursier/version/Version.scala

@@ -145,6 +145,7 @@ object Version {
         case "dev"       => Tag.devLevel
         case "alpha"     => Tag.alphaLevel
         case "beta"      => Tag.betaLevel
+        case "pre"       => Tag.preLevel
         case "milestone" => Tag.milestoneLevel
         case "rc" | "cr" => Tag.rcLevel
         case "snapshot"  => Tag.snapshotLevel
@@ -183,10 +184,12 @@ object Version {
     // Qualifiers, in order. Those below emptyLevel denote pre-releases, those above it
     // denote releases. Unlike Maven, ga and final are distinct, and distinct from the empty
     // item, so that no two of them compare equal and sorting versions stays deterministic.
-    // dev isn't part of the documented ordering, it's kept as an extension, below alpha.
-    private[version] val devLevel       = -6
-    private[version] val alphaLevel     = -5
-    private[version] val betaLevel      = -4
+    // dev and pre aren't part of the documented ordering, they are kept as extensions,
+    // below alpha for dev, and between beta and milestone for pre.
+    private[version] val devLevel       = -7
+    private[version] val alphaLevel     = -6
+    private[version] val betaLevel      = -5
+    private[version] val preLevel       = -4
     private[version] val milestoneLevel = -3
     private[version] val rcLevel        = -2
     private[version] val snapshotLevel  = -1

versions/shared/test/src/coursier/version/VersionCompatibilityTests.scala

@@ -175,9 +175,11 @@ object VersionCompatibilityTests extends TestSuite {
           "1.2.3-beta2",
           "1.2.3-SNAPSHOT",
           "1.2.3-milestone2",
+          "1.2.3-pre2",
           // well-known markers count as pre-releases wherever they show up
           "1.2.3.RC1",
-          "1.2.3.SNAPSHOT"
+          "1.2.3.SNAPSHOT",
+          "1.2.3.pre2"
         )
         for (compat <- compatibilities; wanted <- preReleases) {
           val compatible = compat.isCompatible(wanted, "1.9.9")

versions/shared/test/src/coursier/version/VersionTests.scala

@@ -213,7 +213,8 @@ object VersionTests extends TestSuite {
       assert(compare("1-alpha1", "1-a1" ) == 0)
       assert(compare("1-alpha", "1-beta" ) < 0)
       assert(compare("1-beta1", "1-b1" ) == 0)
-      assert(compare("1-beta", "1-milestone" ) < 0)
+      assert(compare("1-beta", "1-pre" ) < 0)
+      assert(compare("1-pre", "1-milestone" ) < 0)
       assert(compare("1-milestone1", "1-m1" ) == 0)
       assert(compare("1-milestone", "1-rc" ) < 0)
       assert(compare("1-rc", "1-cr" ) == 0)
@@ -257,6 +258,7 @@ object VersionTests extends TestSuite {
       assert(compare("1-abc", "1-alpha" ) > 0)
       assert(compare("1-abc", "1-beta" ) > 0)
       assert(compare("1-abc", "1-milestone" ) > 0)
+      assert(compare("1-abc", "1-pre" ) > 0)
       assert(compare("1-abc", "1-rc" ) > 0)
       assert(compare("1-abc", "1-snapshot" ) > 0)
       assert(compare("1-abc", "1" ) > 0)
@@ -427,6 +429,9 @@ object VersionTests extends TestSuite {
       // M1 is a milestone, while MF, X1 and a are plain literal items, which sort
       // after 1.0 rather than before it
       assert(increasing( "1.0-alpha1", "1.0-M1", "1.0-RC1", "1.0", "1.0-MF", "1.0-X1", "2.0", "2.0.2"))
+      assert(increasing( "1.0.0-alpha3", "1.0.0-beta3", "1.0.0-pre3", "1.0.0-M3", "1.0.0-RC3", "1.0.0" ))
+      assert(increasing( "1.0.0-pre1", "1.0.0-pre2", "1.0.0-PRE10", "1.0.0" ))
+      assert(increasing( "1.0.0.pre3", "1.0.0" ))
       assert(increasing( "1.0-RC1", "1.0", "1.0a", "1.0-MF", "1.0-X1", "2.0", "2.0.2"))
     }
 
@@ -625,8 +630,10 @@ object VersionTests extends TestSuite {
       // cr and rc are two spellings of the same qualifier, so are m1 and milestone1
       assert(compare("1-cr", "1-rc") == 0)
       assert(compare("1-m1", "1-milestone1") == 0)
-      // dev is a coursier extension, it isn't part of the documented list
+      // dev and pre are coursier extensions, they aren't part of the documented list
       assert(compare("1-dev", "1-alpha") < 0)
+      assert(compare("1-beta", "1-pre") < 0)
+      assert(compare("1-pre", "1-milestone") < 0)
     }
   }