Add Version.compare/2

Author: ericmj

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 * Enhancements
   * [Mix] Do not fail if a Mix dependency relies on an outdated Elixir version
+  * [Version] Add `Version.compare/2`
 
 * Bug fixes
   * [Atom] Inspect `:...` and `:foo@bar` without quoting

lib/elixir/lib/version.ex

@@ -225,6 +225,22 @@ defmodule Version do
     Version.Schema[major: major, minor: minor, patch: patch, pre: pre, source: source]
   end
 
+  @spec compare(String.t | Schema.t, String.t | Schema.t) :: :gt | :eq | :lt
+  def compare(vsn1, vsn2) do
+    { major1, minor1, patch1, pre1 } = to_matchable(vsn1)
+    { major2, minor2, patch2, pre2 } = to_matchable(vsn2)
+
+    cond do
+      { major1, minor1, patch1 } > { major2, minor2, patch2 } -> :gt
+      { major1, minor1, patch1 } < { major2, minor2, patch2 } -> :lt
+      pre1 == [] and pre2 != [] -> :gt
+      pre1 != [] and pre2 == [] -> :lt
+      pre1 > pre2 -> :gt
+      pre1 < pre2 -> :lt
+      true -> :eq
+    end
+  end
+
   defmodule Parser.DSL do
     @moduledoc false
 

lib/elixir/test/elixir/version_test.exs

@@ -5,6 +5,32 @@ defmodule VersionTest do
   alias Version.Parser, as: P
   alias Version, as: V
 
+  test "compare" do
+    assert :gt == V.compare("1.0.1",     "1.0.0")
+    assert :gt == V.compare("1.1.0",     "1.0.1")
+    assert :gt == V.compare("2.1.1",     "1.2.2")
+    assert :gt == V.compare("1.0.0",     "1.0.0-dev")
+    assert :gt == V.compare("1.2.3-dev", "0.1.2")
+    assert :gt == V.compare("1.0.0-a.b", "1.0.0-a")
+    assert :gt == V.compare("1.0.0-b",   "1.0.0-a.b")
+    assert :gt == V.compare("1.0.0-a",   "1.0.0-0")
+    assert :gt == V.compare("1.0.0-a.b", "1.0.0-a.a")
+
+    assert :lt == V.compare("1.0.0",     "1.0.1")
+    assert :lt == V.compare("1.0.1",     "1.1.0")
+    assert :lt == V.compare("1.2.2",     "2.1.1")
+    assert :lt == V.compare("1.0.0-dev", "1.0.0")
+    assert :lt == V.compare("0.1.2",     "1.2.3-dev")
+    assert :lt == V.compare("1.0.0-a",   "1.0.0-a.b")
+    assert :lt == V.compare("1.0.0-a.b", "1.0.0-b")
+    assert :lt == V.compare("1.0.0-0",   "1.0.0-a")
+    assert :lt == V.compare("1.0.0-a.a", "1.0.0-a.b")
+
+    assert :eq == V.compare("1.0.0", "1.0.0")
+    assert :eq == V.compare("1.0.0-dev", "1.0.0-dev")
+    assert :eq == V.compare("1.0.0-a", "1.0.0-a")
+  end
+
   test "lexes specifications properly" do
     assert P.lexer("== != > >= < <= ~>", []) == [:'==', :'!=', :'>', :'>=', :'<', :'<=', :'~>']
     assert P.lexer("2.3", []) == [:'==', "2.3"]
@@ -66,6 +92,9 @@ defmodule VersionTest do
     assert V.match?("1.2.3-alpha.beta.sigma", "> 1.2.3-alpha.beta")
     refute V.match?("1.2.3-alpha.10", "< 1.2.3-alpha.1")
     refute V.match?("0.10.2-dev", "> 0.10.2")
+
+    refute V.match?("1.0.0-dev", "> 1.0.0")
+    refute V.match?("0.1.2", "> 1.2.3-dev")
   end
 
   test :>= do
@@ -83,6 +112,9 @@ defmodule VersionTest do
     refute V.match?("2.3", "< 2.3")
 
     assert V.match?("0.10.2-dev", "< 0.10.2")
+
+    refute V.match?("1.0.0", "< 1.0.0-dev")
+    refute V.match?("1.2.3-dev", "< 0.1.2")
   end
 
   test :<= do

lib/mix/test/mix/tasks/app.start_test.exs

@@ -33,8 +33,6 @@ defmodule Mix.Tasks.App.StartTest do
       assert System.version == Mix.Deps.Lock.elixir_vsn
       assert File.stat!("_build/shared/lib/sample/.compile.lock").mtime > { { 2010, 1, 1 }, { 0, 0, 0 } }
     end
-  after
-    Mix.Project.pop
   end
 
   test "compiles and starts the project" do
@@ -53,8 +51,6 @@ defmodule Mix.Tasks.App.StartTest do
       Mix.Tasks.App.Start.run []
       assert List.keyfind(:application.loaded_applications, :app_start_sample, 0)
     end
-  after
-    Mix.Project.pop
   end
 
   test "validates the Elixir version requirement" do
@@ -69,7 +65,6 @@ defmodule Mix.Tasks.App.StartTest do
     end
   after
     purge [A, B, C]
-    Mix.Project.pop
   end
 
   test "does not validate the Elixir version requirement when disabled" do
@@ -80,6 +75,5 @@ defmodule Mix.Tasks.App.StartTest do
     end
   after
     purge [A, B, C]
-    Mix.Project.pop
   end
 end