Auto merge of #5920 - bundler:colby/bundler-list, r=segiddins

implement new list command

### What was the end-user problem that led to this PR?

We're removing the `bundle show` command (which has been replaced with `bundle info`) but we should probably still have a command to list the gems in the bundle.

### What was your diagnosis of the problem?

`bundle show` has been marked as deprecated but a replacement for listing gems does not yet exist

### What is your fix for the problem, implemented in this PR?

Add a new `bundle list` (including `ls` alias) that prints the gems in the bundle, this was taken from #4754

1 files changed, 40 insertions, 0 deletions

diff --git a/spec/commands/list_spec.rb b/spec/commands/list_spec.rb
new file mode 100644
index 0000000000..0ea70f015c
--- /dev/null
+++ b/spec/commands/list_spec.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+RSpec.describe "bundle list", :bundler => "2" do
+  before do
+    install_gemfile <<-G
+      source "file://#{gem_repo1}"
+      gem "rack"
+    G
+  end
+
+  context "with name-only option" do
+    it "prints only the name of the gems in the bundle" do
+      bundle "list --name-only"
+      expect(out).to eq "rack"
+    end
+  end
+
+  context "when no gems are in the gemfile" do
+    before do
+      install_gemfile <<-G
+        source "file://#{gem_repo1}"
+      G
+    end
+
+    it "prints message saying no gems are in the bundle" do
+      bundle "list"
+      expect(out).to include("No gems in the Gemfile")
+    end
+  end
+
+  it "lists gems installed in the bundle" do
+    bundle "list"
+    expect(out).to include("  * rack (1.0.0)")
+  end
+
+  it "aliases the ls command to list" do
+    bundle "ls"
+    expect(out).to include("Gems included by the bundle")
+  end
+end