✨ Fixes handling of empty JSON responses that should not be parsed

- https://gitlab.com/oauth-xx/oauth2/-/issues/641

Author: pboling

.rubocop_gradual.lock

@@ -18,7 +18,7 @@
     [9, 9, 25, "ThreadSafety/ClassInstanceVariable: Avoid class instance variables.", 2012823020],
     [13, 9, 25, "ThreadSafety/ClassInstanceVariable: Avoid class instance variables.", 2012823020]
   ],
-  "lib/oauth2/response.rb:355921218": [
+  "lib/oauth2/response.rb:4048171841": [
     [35, 5, 204, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 996912427]
   ],
   "oauth2.gemspec:290828046": [
@@ -48,7 +48,7 @@
     [69, 15, 38, "RSpec/ContextWording: Context description should match /^when\\b/, /^with\\b/, or /^without\\b/.", 1480816240],
     [79, 13, 23, "RSpec/ContextWording: Context description should match /^when\\b/, /^with\\b/, or /^without\\b/.", 2314399065]
   ],
-  "spec/oauth2/client_spec.rb:1326196445": [
+  "spec/oauth2/client_spec.rb:348683155": [
     [6, 1, 29, "RSpec/SpecFilePathFormat: Spec path should end with `o_auth2/client*_spec.rb`.", 439549885],
     [175, 7, 492, "RSpec/NoExpectationExample: No expectation found in this example.", 1272021224],
     [194, 7, 592, "RSpec/NoExpectationExample: No expectation found in this example.", 3428877205],
@@ -59,13 +59,12 @@
     [830, 5, 360, "RSpec/NoExpectationExample: No expectation found in this example.", 536201463],
     [839, 5, 461, "RSpec/NoExpectationExample: No expectation found in this example.", 3392600621],
     [850, 5, 340, "RSpec/NoExpectationExample: No expectation found in this example.", 244592251],
-    [895, 63, 2, "RSpec/BeEq: Prefer `be` over `eq`.", 5860785],
-    [940, 11, 99, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 3084776886],
-    [944, 11, 82, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 1524553529],
-    [952, 7, 89, "RSpec/NoExpectationExample: No expectation found in this example.", 4609419],
-    [1040, 11, 99, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 3084776886],
-    [1044, 11, 82, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 1524553529],
-    [1124, 17, 12, "RSpec/ContextWording: Context description should match /^when\\b/, /^with\\b/, or /^without\\b/.", 664794325]
+    [978, 11, 99, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 3084776886],
+    [982, 11, 82, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 1524553529],
+    [990, 7, 89, "RSpec/NoExpectationExample: No expectation found in this example.", 4609419],
+    [1078, 11, 99, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 3084776886],
+    [1082, 11, 82, "Style/ClassMethodsDefinitions: Use `class << self` to define a class method.", 1524553529],
+    [1162, 17, 12, "RSpec/ContextWording: Context description should match /^when\\b/, /^with\\b/, or /^without\\b/.", 664794325]
   ],
   "spec/oauth2/error_spec.rb:1209122273": [
     [23, 1, 28, "RSpec/SpecFilePathFormat: Spec path should end with `o_auth2/error*_spec.rb`.", 3385870076],

lib/oauth2/response.rb

@@ -143,11 +143,10 @@ def parser
 end
 
 OAuth2::Response.register_parser(:json, ["application/json", "text/javascript", "application/hal+json", "application/vnd.collection+json", "application/vnd.api+json", "application/problem+json"]) do |body|
-  next body if body.nil?
   next body unless body.respond_to?(:to_str)
 
   body = body.dup.force_encoding(Encoding::ASCII_8BIT) if body.respond_to?(:force_encoding)
-  next body if body.empty?
+  next body if body.respond_to?(:empty?) && body.empty?
 
   JSON.parse(body)
 end

spec/oauth2/client_spec.rb

@@ -883,16 +883,54 @@
       context "when the request body is nil" do
         subject(:get_token) { client.get_token({}) }
 
-        it "raises error JSON::ParserError" do
-          block_is_expected { get_token }.to raise_error(JSON::ParserError)
+        it "does not raise error" do
+          block_is_expected { get_token }.not_to raise_error
         end
 
         context "when extract_access_token raises an exception" do
           let(:status_code) { 200 }
           let(:extract_proc) { proc { |client, hash| raise ArgumentError } }
 
           it "returns a nil :access_token" do
-            expect(client.get_token({}, {}, extract_proc)).to eq(nil)
+            expect(client.get_token({}, {}, extract_proc)).to be_nil
+          end
+        end
+      end
+
+      context "when the request body is empty" do
+        subject(:get_token) { client.get_token({}) }
+
+        let(:body) { "" }
+
+        it "does not raise error" do
+          block_is_expected { get_token }.not_to raise_error
+        end
+
+        context "when extract_access_token raises an exception" do
+          let(:status_code) { 200 }
+          let(:extract_proc) { proc { |client, hash| raise ArgumentError } }
+
+          it "returns a nil :access_token" do
+            expect(client.get_token({}, {}, extract_proc)).to be_nil
+          end
+        end
+      end
+
+      context "when the request body is not valid JSON" do
+        subject(:get_token) { client.get_token({}) }
+
+        let(:body) { "BLOOP" }
+
+        it "raises error" do
+          block_is_expected { get_token }.to raise_error(JSON::ParserError, /unexpected character: 'BLOOP'/)
+        end
+
+        context "when extract_access_token raises an exception" do
+          let(:status_code) { 200 }
+          let(:extract_proc) { proc { |client, hash| raise ArgumentError } }
+
+          it "returns a nil :access_token" do
+            expect(client.get_token({}, {}, extract_proc)).to be_nil
           end
         end
       end