diff --git a/spec/controllers/shopify/callbacks_controller_spec.rb b/spec/controllers/shopify/callbacks_controller_spec.rb
index cb75e23b4..c57440347 100644
--- a/spec/controllers/shopify/callbacks_controller_spec.rb
+++ b/spec/controllers/shopify/callbacks_controller_spec.rb
@@ -9,6 +9,13 @@ RSpec.describe Shopify::CallbacksController, type: :request do
   let(:shopify_redirect_uri) { "#{frontend_url}/app/accounts/#{account.id}/settings/integrations/shopify" }
   let(:oauth_client) { instance_double(OAuth2::Client) }
   let(:auth_code_strategy) { instance_double(OAuth2::Strategy::AuthCode) }
+  let(:token_response) do
+    instance_double(
+      OAuth2::AccessToken,
+      response: instance_double(OAuth2::Response, parsed: response_body),
+      token: access_token
+    )
+  end
 
   describe 'GET /shopify/callback' do
     let(:access_token) { SecureRandom.hex(10) }
@@ -23,12 +30,24 @@ RSpec.describe Shopify::CallbacksController, type: :request do
       stub_const('ENV', ENV.to_hash.merge('FRONTEND_URL' => frontend_url))
     end
 
-    context 'when successful' do
+    shared_context 'with stubbed account' do
       before do
-        controller = described_class.new
-        allow(controller).to receive(:verify_shopify_token).with(state).and_return(account.id)
-        allow(described_class).to receive(:new).and_return(controller)
+        allow(described_class).to receive(:new).and_wrap_original do |original, *args|
+          controller = original.call(*args)
+          allow(controller).to receive(:verify_shopify_token).and_return(account.id)
+          allow(controller).to receive(:oauth_client).and_return(oauth_client)
+          controller
+        end
+        allow(Account).to receive(:find).and_return(account)
 
+        allow(oauth_client).to receive(:auth_code).and_return(auth_code_strategy)
+      end
+    end
+
+    context 'when successful' do
+      include_context 'with stubbed account'
+      before do
+        allow(auth_code_strategy).to receive(:get_token).and_return(token_response)
         stub_request(:post, "https://#{shop}/admin/oauth/access_token")
           .to_return(
             status: 200,
@@ -55,12 +74,11 @@ RSpec.describe Shopify::CallbacksController, type: :request do
     end
 
     context 'when the code is missing' do
+      include_context 'with stubbed account'
       before do
-        controller = described_class.new
-        allow(controller).to receive(:verify_shopify_token).with(state).and_return(account.id)
-        allow(controller).to receive(:oauth_client).and_return(oauth_client)
-        allow(oauth_client).to receive(:auth_code).and_raise(StandardError)
-        allow(described_class).to receive(:new).and_return(controller)
+        allow(auth_code_strategy).to receive(:get_token).and_raise(StandardError)
+        stub_request(:post, "https://#{shop}/admin/oauth/access_token")
+          .to_return(status: 400, body: { error: 'invalid_grant' }.to_json)
       end
 
       it 'redirects to the shopify_redirect_uri with error' do
@@ -70,11 +88,8 @@ RSpec.describe Shopify::CallbacksController, type: :request do
     end
 
     context 'when the token is invalid' do
+      include_context 'with stubbed account'
       before do
-        controller = described_class.new
-        allow(controller).to receive(:verify_shopify_token).with(state).and_return(account.id)
-        allow(controller).to receive(:oauth_client).and_return(oauth_client)
-        allow(oauth_client).to receive(:auth_code).and_return(auth_code_strategy)
         allow(auth_code_strategy).to receive(:get_token).and_raise(
           OAuth2::Error.new(
             OpenStruct.new(
@@ -83,7 +98,9 @@ RSpec.describe Shopify::CallbacksController, type: :request do
             )
           )
         )
-        allow(described_class).to receive(:new).and_return(controller)
+
+        stub_request(:post, "https://#{shop}/admin/oauth/access_token")
+          .to_return(status: 400, body: { error: 'invalid_grant' }.to_json)
       end
 
       it 'redirects to the shopify_redirect_uri with error' do
@@ -94,10 +111,11 @@ RSpec.describe Shopify::CallbacksController, type: :request do
 
     context 'when state parameter is invalid' do
       before do
-        controller = described_class.new
-        allow(controller).to receive(:verify_shopify_token).with(state).and_return(nil)
-        allow(controller).to receive(:account).and_return(nil)
-        allow(described_class).to receive(:new).and_return(controller)
+        # rubocop:disable RSpec/AnyInstance, RSpec/DescribedClass
+        # Explicit class name and any_instance required for parallel CI stability
+        allow_any_instance_of(Shopify::CallbacksController).to receive(:verify_shopify_token).and_return(nil)
+        allow_any_instance_of(Shopify::CallbacksController).to receive(:account).and_return(nil)
+        # rubocop:enable RSpec/AnyInstance, RSpec/DescribedClass
       end
 
       it 'redirects to the frontend URL with error' do
diff --git a/spec/services/crm/leadsquared/api/base_client_spec.rb b/spec/services/crm/leadsquared/api/base_client_spec.rb
index e88fd04c5..132ca81ff 100644
--- a/spec/services/crm/leadsquared/api/base_client_spec.rb
+++ b/spec/services/crm/leadsquared/api/base_client_spec.rb
@@ -63,10 +63,10 @@ RSpec.describe Crm::Leadsquared::Api::BaseClient do
       end
 
       it 'raises ApiError with error message' do
-        expect { client.get(path, params) }.to raise_error(
-          Crm::Leadsquared::Api::BaseClient::ApiError,
-          'Invalid lead ID'
-        )
+        expect { client.get(path, params) }.to raise_error do |error|
+          expect(error.class.name).to eq(described_class::ApiError.name)
+          expect(error.message).to eq('Invalid lead ID')
+        end
       end
     end
 
@@ -82,7 +82,7 @@ RSpec.describe Crm::Leadsquared::Api::BaseClient do
 
       it 'raises ApiError with status code' do
         expect { client.get(path, params) }.to raise_error do |error|
-          expect(error).to be_a(Crm::Leadsquared::Api::BaseClient::ApiError)
+          expect(error.class.name).to eq(described_class::ApiError.name)
           expect(error.message).to include('Not Found')
           expect(error.code).to eq(404)
         end
@@ -134,10 +134,10 @@ RSpec.describe Crm::Leadsquared::Api::BaseClient do
       end
 
       it 'raises ApiError with error message' do
-        expect { client.post(path, params, body) }.to raise_error(
-          Crm::Leadsquared::Api::BaseClient::ApiError,
-          'Invalid data'
-        )
+        expect { client.post(path, params, body) }.to raise_error do |error|
+          expect(error.class.name).to eq(described_class::ApiError.name)
+          expect(error.message).to eq('Invalid data')
+        end
       end
     end
 
@@ -158,7 +158,7 @@ RSpec.describe Crm::Leadsquared::Api::BaseClient do
 
       it 'raises ApiError for invalid JSON' do
         expect { client.post(path, params, body) }.to raise_error do |error|
-          expect(error).to be_a(Crm::Leadsquared::Api::BaseClient::ApiError)
+          expect(error.class.name).to eq(described_class::ApiError.name)
           expect(error.message).to include('Failed to parse')
         end
       end
@@ -177,7 +177,7 @@ RSpec.describe Crm::Leadsquared::Api::BaseClient do
 
       it 'raises ApiError with status code' do
         expect { client.post(path, params, body) }.to raise_error do |error|
-          expect(error).to be_a(Crm::Leadsquared::Api::BaseClient::ApiError)
+          expect(error.class.name).to eq(described_class::ApiError.name)
           expect(error.message).to include('Internal Server Error')
           expect(error.code).to eq(500)
         end