diff --git a/test/net/imap/test_deprecated_client_options.rb b/test/net/imap/test_deprecated_client_options.rb
index e6ac95c8..ceb290dd 100644
--- a/test/net/imap/test_deprecated_client_options.rb
+++ b/test/net/imap/test_deprecated_client_options.rb
@@ -87,31 +87,15 @@ class InitializeTests < DeprecatedClientOptionsTest
     end
 
     test "combined options hash and keyword args raises ArgumentError" do
-      ex = nil
-      run_fake_server_in_thread(
-        ignore_io_error: true, implicit_tls: true
-      ) do |server|
-        imap = Net::IMAP.new("localhost", {port: 993}, ssl: true)
-      rescue => ex
-        nil
-      ensure
-        imap&.disconnect
+      assert_raise_with_message ArgumentError, /deprecated.*keyword arg/ do
+        Net::IMAP.new("localhost", {port: 993}, ssl: true)
       end
-      assert_equal ArgumentError, ex.class
     end
 
     test "combined options hash and ssl args raises ArgumentError" do
-      ex = nil
-      run_fake_server_in_thread(
-        ignore_io_error: true, implicit_tls: true
-      ) do |server|
-        imap = Net::IMAP.new("localhost", {port: 993}, true)
-      rescue => ex
-        nil
-      ensure
-        imap&.disconnect
+      assert_raise_with_message ArgumentError, /deprecated SSL.*options hash/ do
+        Net::IMAP.new("localhost", {port: 993}, true)
       end
-      assert_equal ArgumentError, ex.class
     end
 
   end
diff --git a/test/net/imap/test_fetch_data.rb b/test/net/imap/test_fetch_data.rb
index 7776f25c..bcbbf50c 100644
--- a/test/net/imap/test_fetch_data.rb
+++ b/test/net/imap/test_fetch_data.rb
@@ -36,20 +36,24 @@ def fetch_data_class
     assert_equal 22222, data.uid
   end
 
-  test "#uid warns when differs from UID attribute" do
-    data = nil
+  test "#initialize warns when uid differs from attr['UID']" do
     assert_warn(/UIDs do not match/i) do
-      data = Net::IMAP::UIDFetchData.new(22222, "UID" => 54_321)
+      Net::IMAP::UIDFetchData.new(22222, "UID" => 54_321)
     end
+  end
+
+  test "#uid ignores the UID attribute" do
+    data = EnvUtil.suppress_warning {
+      Net::IMAP::UIDFetchData.new(22222, "UID" => 54_321)
+    }
     assert_equal 22222, data.uid
   end
 
   test "#deconstruct_keys" do
-    assert_warn(/UIDs do not match/i) do
-      Net::IMAP::UIDFetchData.new(22222, "UID" => 54_321) => {
-        uid: 22222
-      }
-    end
+    data = EnvUtil.suppress_warning {
+      Net::IMAP::UIDFetchData.new(22222, "UID" => 54_321)
+    }
+    assert_pattern { data => { uid: 22222 } }
   end
 end
 
diff --git a/test/net/imap/test_response_reader.rb b/test/net/imap/test_response_reader.rb
index 5d64c07a..cec6768e 100644
--- a/test/net/imap/test_response_reader.rb
+++ b/test/net/imap/test_response_reader.rb
@@ -55,13 +55,33 @@ def literal(str) = "{#{str.bytesize}}\r\n#{str}"
     client.config.max_response_size = 10
     under = "+ 3456\r\n"
     exact = "+ 345678\r\n"
-    over  = "+ 3456789\r\n"
-    io = StringIO.new([under, exact, over].join)
+    very_over     = "+ 3456789 #{?a * (16<<10)}}\r\n"
+    slightly_over = "+ 34567890\r\n" # CRLF after the limit
+    io = StringIO.new([under, exact, very_over, slightly_over].join)
     rcvr = Net::IMAP::ResponseReader.new(client, io)
     assert_equal under, rcvr.read_response_buffer.to_str
     assert_equal exact, rcvr.read_response_buffer.to_str
     assert_raise Net::IMAP::ResponseTooLargeError do
-      rcvr.read_response_buffer
+      result = rcvr.read_response_buffer
+      flunk "Got result: %p" % [result]
+    end
+    io = StringIO.new(slightly_over)
+    rcvr = Net::IMAP::ResponseReader.new(client, io)
+    assert_raise Net::IMAP::ResponseTooLargeError do
+      result = rcvr.read_response_buffer
+      flunk "Got result: %p" % [result]
+    end
+  end
+
+  test "#read_response_buffer max_response_size straddling CRLF" do
+    barely_over = "+ 3456789\r\n"  # CRLF straddles the boundary
+    client = FakeClient.new
+    client.config.max_response_size = 10
+    io = StringIO.new(barely_over)
+    rcvr = Net::IMAP::ResponseReader.new(client, io)
+    assert_raise Net::IMAP::ResponseTooLargeError do
+      result = rcvr.read_response_buffer
+      flunk "Got result: %p" % [result]
     end
   end