diff --git a/internal/handlers/ussd/menuhandler.go b/internal/handlers/ussd/menuhandler.go
index b01869b..805dcff 100644
--- a/internal/handlers/ussd/menuhandler.go
+++ b/internal/handlers/ussd/menuhandler.go
@@ -29,11 +29,6 @@ var (
 	translationDir = path.Join(scriptDir, "locale")
 )
 
-type FSData struct {
-	Path string
-	St   *state.State
-}
-
 // FlagManager handles centralized flag management
 type FlagManager struct {
 	parser *asm.FlagParser
diff --git a/internal/handlers/ussd/menuhandler_test.go b/internal/handlers/ussd/menuhandler_test.go
index dd24b20..d0367f0 100644
--- a/internal/handlers/ussd/menuhandler_test.go
+++ b/internal/handlers/ussd/menuhandler_test.go
@@ -11,7 +11,7 @@ import (
 	"git.defalsify.org/vise.git/db"
 	"git.defalsify.org/vise.git/resource"
 	"git.defalsify.org/vise.git/state"
-	"git.grassecon.net/urdt/ussd/internal/handlers/ussd/mocks"
+	"git.grassecon.net/urdt/ussd/internal/mocks"
 	"git.grassecon.net/urdt/ussd/internal/models"
 	"git.grassecon.net/urdt/ussd/internal/utils"
 	"github.com/alecthomas/assert/v2"
diff --git a/internal/http/at_session_handler.go b/internal/http/at_session_handler.go
index 4a0cafa..53c4ba2 100644
--- a/internal/http/at_session_handler.go
+++ b/internal/http/at_session_handler.go
@@ -32,6 +32,7 @@ func (ash *ATSessionHandler) ServeHTTP(w http.ResponseWriter, req *http.Request)
 	if err != nil {
 		logg.ErrorCtxf(rqs.Ctx, "", "header processing error", err)
 		ash.writeError(w, 400, err)
+		return
 	}
 	rqs.Config = cfg
 	rqs.Input, err = rp.GetInput(req)
@@ -41,16 +42,14 @@ func (ash *ATSessionHandler) ServeHTTP(w http.ResponseWriter, req *http.Request)
 		return
 	}
 
-	rqs, err = ash.Process(rqs)
+	rqs, err = ash.Process(rqs) 
 	switch err {
-	case handlers.ErrStorage:
-		code = 500
-	case handlers.ErrEngineInit:
-		code = 500
-	case handlers.ErrEngineExec:
+	case nil: // set code to 200 if no err
+		code = 200
+	case handlers.ErrStorage, handlers.ErrEngineInit, handlers.ErrEngineExec, handlers.ErrEngineType:
 		code = 500
 	default:
-		code = 200
+		code = 500
 	}
 
 	if code != 200 {
diff --git a/internal/http/http_test.go b/internal/http/http_test.go
new file mode 100644
index 0000000..48d04ca
--- /dev/null
+++ b/internal/http/http_test.go
@@ -0,0 +1,449 @@
+package http
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+
+	"git.defalsify.org/vise.git/engine"
+	"git.grassecon.net/urdt/ussd/internal/handlers"
+	"git.grassecon.net/urdt/ussd/internal/mocks/httpmocks"
+)
+
+// invalidRequestType is a custom type to test invalid request scenarios
+type invalidRequestType struct{}
+
+// errorReader is a helper type that always returns an error when Read is called
+type errorReader struct{}
+
+func (e *errorReader) Read(p []byte) (n int, err error) {
+	return 0, errors.New("read error")
+}
+
+func TestNewATSessionHandler(t *testing.T) {
+	mockHandler := &httpmocks.MockRequestHandler{}
+	ash := NewATSessionHandler(mockHandler)
+
+	if ash == nil {
+		t.Fatal("NewATSessionHandler returned nil")
+	}
+
+	if ash.SessionHandler == nil {
+		t.Fatal("SessionHandler is nil")
+	}
+}
+
+func TestATSessionHandler_ServeHTTP(t *testing.T) {
+	tests := []struct {
+		name           string
+		setupMocks     func(*httpmocks.MockRequestHandler, *httpmocks.MockRequestParser, *httpmocks.MockEngine)
+		formData       url.Values
+		expectedStatus int
+		expectedBody   string
+	}{
+		{
+			name: "Successful request",
+			setupMocks: func(mh *httpmocks.MockRequestHandler, mrp *httpmocks.MockRequestParser, me *httpmocks.MockEngine) {
+				mrp.GetSessionIdFunc = func(rq any) (string, error) {
+					req := rq.(*http.Request)
+					return req.FormValue("phoneNumber"), nil
+				}
+				mrp.GetInputFunc = func(rq any) ([]byte, error) {
+					req := rq.(*http.Request)
+					text := req.FormValue("text")
+					parts := strings.Split(text, "*")
+					return []byte(parts[len(parts)-1]), nil
+				}
+				mh.ProcessFunc = func(rqs handlers.RequestSession) (handlers.RequestSession, error) {
+					rqs.Continue = true
+					rqs.Engine = me
+					return rqs, nil
+				}
+				mh.GetConfigFunc = func() engine.Config { return engine.Config{} }
+				mh.GetRequestParserFunc = func() handlers.RequestParser { return mrp }
+				mh.OutputFunc = func(rs handlers.RequestSession) (handlers.RequestSession, error) { return rs, nil }
+				mh.ResetFunc = func(rs handlers.RequestSession) (handlers.RequestSession, error) { return rs, nil }
+				me.WriteResultFunc = func(context.Context, io.Writer) (int, error) { return 0, nil }
+			},
+			formData: url.Values{
+				"phoneNumber": []string{"+1234567890"},
+				"text":        []string{"1*2*3"},
+			},
+			expectedStatus: http.StatusOK,
+			expectedBody:   "CON ",
+		},
+		{
+			name: "GetSessionId error",
+			setupMocks: func(mh *httpmocks.MockRequestHandler, mrp *httpmocks.MockRequestParser, me *httpmocks.MockEngine) {
+				mrp.GetSessionIdFunc = func(rq any) (string, error) {
+					return "", errors.New("no phone number found")
+				}
+				mh.GetConfigFunc = func() engine.Config { return engine.Config{} }
+				mh.GetRequestParserFunc = func() handlers.RequestParser { return mrp }
+			},
+			formData: url.Values{
+				"text": []string{"1*2*3"},
+			},
+			expectedStatus: http.StatusBadRequest,
+			expectedBody:   "",
+		},
+		{
+			name: "GetInput error",
+			setupMocks: func(mh *httpmocks.MockRequestHandler, mrp *httpmocks.MockRequestParser, me *httpmocks.MockEngine) {
+				mrp.GetSessionIdFunc = func(rq any) (string, error) {
+					req := rq.(*http.Request)
+					return req.FormValue("phoneNumber"), nil
+				}
+				mrp.GetInputFunc = func(rq any) ([]byte, error) {
+					return nil, errors.New("no input found")
+				}
+				mh.GetConfigFunc = func() engine.Config { return engine.Config{} }
+				mh.GetRequestParserFunc = func() handlers.RequestParser { return mrp }
+			},
+			formData: url.Values{
+				"phoneNumber": []string{"+1234567890"},
+			},
+			expectedStatus: http.StatusBadRequest,
+			expectedBody:   "",
+		},
+		{
+			name: "Process error",
+			setupMocks: func(mh *httpmocks.MockRequestHandler, mrp *httpmocks.MockRequestParser, me *httpmocks.MockEngine) {
+				mrp.GetSessionIdFunc = func(rq any) (string, error) {
+					req := rq.(*http.Request)
+					return req.FormValue("phoneNumber"), nil
+				}
+				mrp.GetInputFunc = func(rq any) ([]byte, error) {
+					req := rq.(*http.Request)
+					text := req.FormValue("text")
+					parts := strings.Split(text, "*")
+					return []byte(parts[len(parts)-1]), nil
+				}
+				mh.ProcessFunc = func(rqs handlers.RequestSession) (handlers.RequestSession, error) {
+					return rqs, handlers.ErrStorage
+				}
+				mh.GetConfigFunc = func() engine.Config { return engine.Config{} }
+				mh.GetRequestParserFunc = func() handlers.RequestParser { return mrp }
+			},
+			formData: url.Values{
+				"phoneNumber": []string{"+1234567890"},
+				"text":        []string{"1*2*3"},
+			},
+			expectedStatus: http.StatusInternalServerError,
+			expectedBody:   "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mockHandler := &httpmocks.MockRequestHandler{}
+			mockRequestParser := &httpmocks.MockRequestParser{}
+			mockEngine := &httpmocks.MockEngine{}
+			tt.setupMocks(mockHandler, mockRequestParser, mockEngine)
+
+			ash := NewATSessionHandler(mockHandler)
+
+			req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader(tt.formData.Encode()))
+			req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+			w := httptest.NewRecorder()
+
+			ash.ServeHTTP(w, req)
+
+			if w.Code != tt.expectedStatus {
+				t.Errorf("Expected status %d, got %d", tt.expectedStatus, w.Code)
+			}
+
+			if tt.expectedBody != "" && w.Body.String() != tt.expectedBody {
+				t.Errorf("Expected body %q, got %q", tt.expectedBody, w.Body.String())
+			}
+		})
+	}
+}
+
+func TestATSessionHandler_Output(t *testing.T) {
+	tests := []struct {
+		name           string
+		input          handlers.RequestSession
+		expectedPrefix string
+		expectedError  bool
+	}{
+		{
+			name: "Continue true",
+			input: handlers.RequestSession{
+				Continue: true,
+				Engine: &httpmocks.MockEngine{
+					WriteResultFunc: func(context.Context, io.Writer) (int, error) {
+						return 0, nil
+					},
+				},
+				Writer: &httpmocks.MockWriter{},
+			},
+			expectedPrefix: "CON ",
+			expectedError:  false,
+		},
+		{
+			name: "Continue false",
+			input: handlers.RequestSession{
+				Continue: false,
+				Engine: &httpmocks.MockEngine{
+					WriteResultFunc: func(context.Context, io.Writer) (int, error) {
+						return 0, nil
+					},
+				},
+				Writer: &httpmocks.MockWriter{},
+			},
+			expectedPrefix: "END ",
+			expectedError:  false,
+		},
+		{
+			name: "WriteResult error",
+			input: handlers.RequestSession{
+				Continue: true,
+				Engine: &httpmocks.MockEngine{
+					WriteResultFunc: func(context.Context, io.Writer) (int, error) {
+						return 0, errors.New("write error")
+					},
+				},
+				Writer: &httpmocks.MockWriter{},
+			},
+			expectedPrefix: "CON ",
+			expectedError:  true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ash := &ATSessionHandler{}
+			_, err := ash.Output(tt.input)
+
+			if tt.expectedError && err == nil {
+				t.Error("Expected an error, but got nil")
+			}
+
+			if !tt.expectedError && err != nil {
+				t.Errorf("Unexpected error: %v", err)
+			}
+
+			mw := tt.input.Writer.(*httpmocks.MockWriter)
+			if !mw.WriteStringCalled {
+				t.Error("WriteString was not called")
+			}
+
+			if mw.WrittenString != tt.expectedPrefix {
+				t.Errorf("Expected prefix %q, got %q", tt.expectedPrefix, mw.WrittenString)
+			}
+		})
+	}
+}
+
+func TestSessionHandler_ServeHTTP(t *testing.T) {
+	tests := []struct {
+		name           string
+		sessionID      string
+		input          []byte
+		parserErr      error
+		processErr     error
+		outputErr      error
+		resetErr       error
+		expectedStatus int
+	}{
+		{
+			name:           "Success",
+			sessionID:      "123",
+			input:          []byte("test input"),
+			expectedStatus: http.StatusOK,
+		},
+		{
+			name:           "Missing Session ID",
+			sessionID:      "",
+			parserErr:      handlers.ErrSessionMissing,
+			expectedStatus: http.StatusBadRequest,
+		},
+		{
+			name:           "Process Error",
+			sessionID:      "123",
+			input:          []byte("test input"),
+			processErr:     handlers.ErrStorage,
+			expectedStatus: http.StatusInternalServerError,
+		},
+		{
+			name:           "Output Error",
+			sessionID:      "123",
+			input:          []byte("test input"),
+			outputErr:      errors.New("output error"),
+			expectedStatus: http.StatusOK,
+		},
+		{
+			name:           "Reset Error",
+			sessionID:      "123",
+			input:          []byte("test input"),
+			resetErr:       errors.New("reset error"),
+			expectedStatus: http.StatusOK,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mockRequestParser := &httpmocks.MockRequestParser{
+				GetSessionIdFunc: func(any) (string, error) {
+					return tt.sessionID, tt.parserErr
+				},
+				GetInputFunc: func(any) ([]byte, error) {
+					return tt.input, nil
+				},
+			}
+
+			mockRequestHandler := &httpmocks.MockRequestHandler{
+				ProcessFunc: func(rs handlers.RequestSession) (handlers.RequestSession, error) {
+					return rs, tt.processErr
+				},
+				OutputFunc: func(rs handlers.RequestSession) (handlers.RequestSession, error) {
+					return rs, tt.outputErr
+				},
+				ResetFunc: func(rs handlers.RequestSession) (handlers.RequestSession, error) {
+					return rs, tt.resetErr
+				},
+				GetRequestParserFunc: func() handlers.RequestParser {
+					return mockRequestParser
+				},
+				GetConfigFunc: func() engine.Config {
+					return engine.Config{}
+				},
+			}
+
+			sessionHandler := ToSessionHandler(mockRequestHandler)
+
+			req := httptest.NewRequest(http.MethodPost, "/", bytes.NewBuffer(tt.input))
+			req.Header.Set("X-Vise-Session", tt.sessionID)
+
+			rr := httptest.NewRecorder()
+
+			sessionHandler.ServeHTTP(rr, req)
+
+			if status := rr.Code; status != tt.expectedStatus {
+				t.Errorf("handler returned wrong status code: got %v want %v",
+					status, tt.expectedStatus)
+			}
+		})
+	}
+}
+
+func TestSessionHandler_writeError(t *testing.T) {
+	handler := &SessionHandler{}
+	mockWriter := &httpmocks.MockWriter{}
+	err := errors.New("test error")
+
+	handler.writeError(mockWriter, http.StatusBadRequest, err)
+
+	if mockWriter.WrittenString != "" {
+		t.Errorf("Expected empty body, got %s", mockWriter.WrittenString)
+	}
+}
+
+func TestDefaultRequestParser_GetSessionId(t *testing.T) {
+	tests := []struct {
+		name          string
+		request       any
+		expectedID    string
+		expectedError error
+	}{
+		{
+			name: "Valid Session ID",
+			request: func() *http.Request {
+				req := httptest.NewRequest(http.MethodPost, "/", nil)
+				req.Header.Set("X-Vise-Session", "123456")
+				return req
+			}(),
+			expectedID:    "123456",
+			expectedError: nil,
+		},
+		{
+			name:          "Missing Session ID",
+			request:       httptest.NewRequest(http.MethodPost, "/", nil),
+			expectedID:    "",
+			expectedError: handlers.ErrSessionMissing,
+		},
+		{
+			name:          "Invalid Request Type",
+			request:       invalidRequestType{},
+			expectedID:    "",
+			expectedError: handlers.ErrInvalidRequest,
+		},
+	}
+
+	parser := &DefaultRequestParser{}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			id, err := parser.GetSessionId(tt.request)
+
+			if id != tt.expectedID {
+				t.Errorf("Expected session ID %s, got %s", tt.expectedID, id)
+			}
+
+			if err != tt.expectedError {
+				t.Errorf("Expected error %v, got %v", tt.expectedError, err)
+			}
+		})
+	}
+}
+
+func TestDefaultRequestParser_GetInput(t *testing.T) {
+	tests := []struct {
+		name          string
+		request       any
+		expectedInput []byte
+		expectedError error
+	}{
+		{
+			name: "Valid Input",
+			request: func() *http.Request {
+				return httptest.NewRequest(http.MethodPost, "/", bytes.NewBufferString("test input"))
+			}(),
+			expectedInput: []byte("test input"),
+			expectedError: nil,
+		},
+		{
+			name:          "Empty Input",
+			request:       httptest.NewRequest(http.MethodPost, "/", nil),
+			expectedInput: []byte{},
+			expectedError: nil,
+		},
+		{
+			name:          "Invalid Request Type",
+			request:       invalidRequestType{},
+			expectedInput: nil,
+			expectedError: handlers.ErrInvalidRequest,
+		},
+		{
+			name: "Read Error",
+			request: func() *http.Request {
+				return httptest.NewRequest(http.MethodPost, "/", &errorReader{})
+			}(),
+			expectedInput: nil,
+			expectedError: errors.New("read error"),
+		},
+	}
+
+	parser := &DefaultRequestParser{}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			input, err := parser.GetInput(tt.request)
+
+			if !bytes.Equal(input, tt.expectedInput) {
+				t.Errorf("Expected input %s, got %s", tt.expectedInput, input)
+			}
+
+			if err != tt.expectedError && (err == nil || err.Error() != tt.expectedError.Error()) {
+				t.Errorf("Expected error %v, got %v", tt.expectedError, err)
+			}
+		})
+	}
+}
diff --git a/internal/handlers/ussd/mocks/dbmock.go b/internal/mocks/dbmock.go
similarity index 100%
rename from internal/handlers/ussd/mocks/dbmock.go
rename to internal/mocks/dbmock.go
diff --git a/internal/mocks/httpmocks/enginemock.go b/internal/mocks/httpmocks/enginemock.go
new file mode 100644
index 0000000..d5c6b20
--- /dev/null
+++ b/internal/mocks/httpmocks/enginemock.go
@@ -0,0 +1,30 @@
+package httpmocks
+
+import (
+	"context"
+	"io"
+)
+
+// MockEngine implements the engine.Engine interface for testing
+type MockEngine struct {
+	InitFunc        func(context.Context) (bool, error)
+	ExecFunc        func(context.Context, []byte) (bool, error)
+	WriteResultFunc func(context.Context, io.Writer) (int, error)
+	FinishFunc      func() error
+}
+
+func (m *MockEngine) Init(ctx context.Context) (bool, error) {
+	return m.InitFunc(ctx)
+}
+
+func (m *MockEngine) Exec(ctx context.Context, input []byte) (bool, error) {
+	return m.ExecFunc(ctx, input)
+}
+
+func (m *MockEngine) WriteResult(ctx context.Context, w io.Writer) (int, error) {
+	return m.WriteResultFunc(ctx, w)
+}
+
+func (m *MockEngine) Finish() error {
+	return m.FinishFunc()
+}
diff --git a/internal/mocks/httpmocks/requesthandlermock.go b/internal/mocks/httpmocks/requesthandlermock.go
new file mode 100644
index 0000000..f17abce
--- /dev/null
+++ b/internal/mocks/httpmocks/requesthandlermock.go
@@ -0,0 +1,47 @@
+package httpmocks
+
+import (
+	"git.defalsify.org/vise.git/engine"
+	"git.defalsify.org/vise.git/persist"
+	"git.defalsify.org/vise.git/resource"
+	"git.grassecon.net/urdt/ussd/internal/handlers"
+)
+
+// MockRequestHandler implements handlers.RequestHandler interface for testing
+type MockRequestHandler struct {
+	ProcessFunc          func(handlers.RequestSession) (handlers.RequestSession, error)
+	GetConfigFunc        func() engine.Config
+	GetEngineFunc        func(cfg engine.Config, rs resource.Resource, pe *persist.Persister) engine.Engine
+	OutputFunc           func(rs handlers.RequestSession) (handlers.RequestSession, error)
+	ResetFunc            func(rs handlers.RequestSession) (handlers.RequestSession, error)
+	ShutdownFunc         func()
+	GetRequestParserFunc func() handlers.RequestParser
+}
+
+func (m *MockRequestHandler) Process(rqs handlers.RequestSession) (handlers.RequestSession, error) {
+	return m.ProcessFunc(rqs)
+}
+
+func (m *MockRequestHandler) GetConfig() engine.Config {
+	return m.GetConfigFunc()
+}
+
+func (m *MockRequestHandler) GetEngine(cfg engine.Config, rs resource.Resource, pe *persist.Persister) engine.Engine {
+	return m.GetEngineFunc(cfg, rs, pe)
+}
+
+func (m *MockRequestHandler) Output(rs handlers.RequestSession) (handlers.RequestSession, error) {
+	return m.OutputFunc(rs)
+}
+
+func (m *MockRequestHandler) Reset(rs handlers.RequestSession) (handlers.RequestSession, error) {
+	return m.ResetFunc(rs)
+}
+
+func (m *MockRequestHandler) Shutdown() {
+	m.ShutdownFunc()
+}
+
+func (m *MockRequestHandler) GetRequestParser() handlers.RequestParser {
+	return m.GetRequestParserFunc()
+}
diff --git a/internal/mocks/httpmocks/requestparsermock.go b/internal/mocks/httpmocks/requestparsermock.go
new file mode 100644
index 0000000..54b16bf
--- /dev/null
+++ b/internal/mocks/httpmocks/requestparsermock.go
@@ -0,0 +1,15 @@
+package httpmocks
+
+// MockRequestParser implements the handlers.RequestParser interface for testing
+type MockRequestParser struct {
+	GetSessionIdFunc func(any) (string, error)
+	GetInputFunc     func(any) ([]byte, error)
+}
+
+func (m *MockRequestParser) GetSessionId(rq any) (string, error) {
+	return m.GetSessionIdFunc(rq)
+}
+
+func (m *MockRequestParser) GetInput(rq any) ([]byte, error) {
+	return m.GetInputFunc(rq)
+}
diff --git a/internal/mocks/httpmocks/writermock.go b/internal/mocks/httpmocks/writermock.go
new file mode 100644
index 0000000..0d171d2
--- /dev/null
+++ b/internal/mocks/httpmocks/writermock.go
@@ -0,0 +1,25 @@
+package httpmocks
+
+import "net/http"
+
+// MockWriter implements a mock io.Writer for testing
+type MockWriter struct {
+	WriteStringCalled bool
+	WrittenString     string
+}
+
+func (m *MockWriter) Write(p []byte) (n int, err error) {
+	return len(p), nil
+}
+
+func (m *MockWriter) WriteString(s string) (n int, err error) {
+	m.WriteStringCalled = true
+	m.WrittenString = s
+	return len(s), nil
+}
+
+func (m *MockWriter) Header() http.Header {
+	return http.Header{}
+}
+
+func (m *MockWriter) WriteHeader(statusCode int) {}
\ No newline at end of file
diff --git a/internal/handlers/ussd/mocks/servicemock.go b/internal/mocks/servicemock.go
similarity index 100%
rename from internal/handlers/ussd/mocks/servicemock.go
rename to internal/mocks/servicemock.go
diff --git a/internal/handlers/ussd/mocks/userdbmock.go b/internal/mocks/userdbmock.go
similarity index 100%
rename from internal/handlers/ussd/mocks/userdbmock.go
rename to internal/mocks/userdbmock.go