Adds IdentityToken tests and documentation for generating identity tokens

Author: cakejelly

README.md

@@ -142,6 +142,19 @@ layer.block_user("owner_id", "user_id")
 layer.unblock_user("owner_id", "user_id")
 ```
 
+### Generating Identity Tokens
+See: [the official authentication guide](https://developer.layer.com/docs/android/guides#authentication)
+
+Make sure the following environment variables are set:
+`ENV['LAYER_KEY_ID']`
+`ENV['LAYER_PROVIDER_ID']`
+`ENV['LAYER_PRIVATE_KEY']`
+
+```ruby
+# Returns a valid signed identity token.
+layer.generate_identity_token(user_id: "1234", nonce: "your_random_nonce")
+```
+
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake rspec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.

spec/layer/identity_token_spec.rb

@@ -0,0 +1,54 @@
+require 'spec_helper'
+
+describe Layer::Api::IdentityToken do
+  describe ".new" do
+    it "should allow you to set the user_id, nonce and expires_at variables" do
+      user_id = "1234"
+      nonce = "your_random_nonce"
+      expires_at = "12345678"
+
+      # layer = Layer::Api::Client.new
+      token = Layer::Api::IdentityToken.new(
+        user_id: user_id,
+        nonce: nonce,
+        expires_at: expires_at
+      )
+
+      expect(token.user_id).to eq(user_id)
+      expect(token.nonce).to eq(nonce)
+      expect(token.expires_at).to eq(expires_at)
+    end
+  end
+
+  describe ".layer_key_id" do
+    it "should return your ENV['LAYER_KEY_ID']" do
+      layer_key_id = Layer::Api::IdentityToken.new.layer_key_id
+      expect(layer_key_id).to eq(ENV['LAYER_KEY_ID'])
+    end
+  end
+
+  describe ".layer_provider_id" do
+    it "should return your ENV['LAYER_PROVIDER_ID']" do
+      provider_id = Layer::Api::IdentityToken.new.layer_provider_id
+      expect(provider_id).to eq(ENV['LAYER_PROVIDER_ID'])
+    end
+  end
+
+  describe ".get_jwt" do
+  end
+
+  describe ".headers" do
+  end
+
+  describe ".claim" do
+  end
+
+  describe ".private_key" do
+  end
+
+  describe ".to_s" do
+  end
+
+  describe ".generate_identity_token" do
+  end
+end