Add specs for override: list options

Author: TylerWitt

lib/mix/lib/mix/dep.ex

@@ -347,7 +347,7 @@ defmodule Mix.Dep do
       dep_status(dep) <>
       "\n  does not match the requirement specified\n" <>
       dep_status(other) <>
-      "\n  Ensure they match or specify one of the above in your deps and set \"override: true\""
+      "\n  Ensure they match or specify one of the above in your deps and set \"override: [#{inspect(other.app)}]\""
   end
 
   def format_status(%Mix.Dep{app: app, status: {:divergedonly, other}} = dep) do

lib/mix/lib/mix/tasks/deps.ex

@@ -99,7 +99,11 @@ defmodule Mix.Tasks.Deps do
       targets (like `[:host, :rpi3]`)
 
     * `:override` - if set to `true` the dependency will override any other
-      definitions of itself by other dependencies
+      definitions of itself by other dependencies. This option can also be a
+      list, which overrides the definitions of only certain dependencies. If
+      a dependency is not included in the list and an override is required,
+      it will still fail. If a dependency is in the list and no longer necessary,
+      then a warning is emitted
 
     * `:manager` - Mix can also compile Rebar3 and makefile projects
       and can fetch sub dependencies of Rebar3 projects. Mix will

lib/mix/test/mix/dep_test.exs

@@ -1266,6 +1266,47 @@ defmodule Mix.DepTest do
     end
   end
 
+  describe "override_for" do
+    test "warns when overrides are no longer needed for an app" do
+      deps = [
+        {:deps_repo, "0.1.0", path: "custom/deps_repo"},
+        {:git_repo, "0.1.0",
+         git: MixTest.Case.fixture_path("git_repo"), override_for: [:deps_repo]}
+      ]
+
+      with_deps(deps, fn ->
+        in_fixture("deps_status", fn ->
+          Mix.Tasks.Deps.Get.run([])
+          Mix.Tasks.Deps.Compile.run([])
+        end)
+      end)
+
+      message =
+        "Dependency git_repo (#{fixture_path("git_repo")}) no longer requires override_for on deps_repo"
+
+      assert_received {:mix_shell, :info, [^message]}
+    end
+
+    test "errors when more overrides are needed for an app" do
+      deps = [
+        {:deps_repo, "0.1.0", path: "custom/deps_repo"},
+        {:git_repo, "0.2.0", git: MixTest.Case.fixture_path("git_repo"), override_for: []}
+      ]
+
+      with_deps(deps, fn ->
+        in_fixture("deps_status", fn ->
+          Mix.Tasks.Deps.Get.run([])
+          Mix.Tasks.Deps.Compile.run([])
+        end)
+      end)
+
+      message =
+        "Dependency git_repo (#{fixture_path("git_repo")}) requires override_for on deps_repo"
+
+      assert_received {:mix_shell, :info, [^message]}
+    end
+  end
+
   describe "app generation" do
     test "considers runtime from current app on nested deps" do
       Process.put(:custom_deps_git_repo_opts, runtime: false)