diff --git a/src/modules/hash/commands_test.go b/src/modules/hash/commands_test.go
index 6050df14..eab272e5 100644
--- a/src/modules/hash/commands_test.go
+++ b/src/modules/hash/commands_test.go
@@ -1,15 +1,143 @@
 package hash
 
 import (
+	"bytes"
+	"context"
+	"errors"
+	"github.com/echovault/echovault/src/server"
+	"github.com/echovault/echovault/src/utils"
+	"github.com/tidwall/resp"
 	"testing"
 )
 
 func Test_HandleHSET(t *testing.T) {
-	// TODO: test HSET and HSETNX
+	// Tests for both HSET and HSETNX
+	mockServer := server.NewServer(server.Opts{})
+
+	tests := []struct {
+		preset           bool
+		key              string
+		presetValue      interface{}
+		command          []string
+		expectedResponse int // Change count
+		expectedValue    map[string]interface{}
+		expectedError    error
+	}{
+		{ // HSETNX set field on non-existent hash map
+			preset:           false,
+			key:              "key1",
+			presetValue:      map[string]interface{}{},
+			command:          []string{"HSETNX", "key1", "field1", "value1"},
+			expectedResponse: 1,
+			expectedValue:    map[string]interface{}{"field1": "value1"},
+			expectedError:    nil,
+		},
+		{ // HSETNX set field on existing hash map
+			preset:           true,
+			key:              "key2",
+			presetValue:      map[string]interface{}{"field1": "value1"},
+			command:          []string{"HSETNX", "key2", "field2", "value2"},
+			expectedResponse: 1,
+			expectedValue:    map[string]interface{}{"field1": "value1", "field2": "value2"},
+			expectedError:    nil,
+		},
+		{ // HSETNX skips operation when setting on existing field
+			preset:           true,
+			key:              "key3",
+			presetValue:      map[string]interface{}{"field1": "value1"},
+			command:          []string{"HSETNX", "key3", "field1", "value1-new"},
+			expectedResponse: 0,
+			expectedValue:    map[string]interface{}{"field1": "value1"},
+			expectedError:    nil,
+		},
+		{ // Regular HSET command on non-existent hash map
+			preset:           false,
+			key:              "key4",
+			presetValue:      map[string]interface{}{},
+			command:          []string{"HSET", "key4", "field1", "value1", "field2", "value2"},
+			expectedResponse: 2,
+			expectedValue:    map[string]interface{}{"field1": "value1", "field2": "value2"},
+			expectedError:    nil,
+		},
+		{ // Regular HSET update on existing hash map
+			preset:           true,
+			key:              "key5",
+			presetValue:      map[string]interface{}{"field1": "value1", "field2": "value2"},
+			command:          []string{"HSET", "key5", "field1", "value1-new", "field2", "value2-ne2", "field3", "value3"},
+			expectedResponse: 3,
+			expectedValue:    map[string]interface{}{"field1": "value1-new", "field2": "value2-ne2", "field3": "value3"},
+			expectedError:    nil,
+		},
+		{ // HSET returns error when the target key is not a map
+			preset:           true,
+			key:              "key6",
+			presetValue:      "Default preset value",
+			command:          []string{"HSET", "key6", "field1", "value1"},
+			expectedResponse: 0,
+			expectedValue:    map[string]interface{}{},
+			expectedError:    errors.New("value at key6 is not a hash"),
+		},
+		{ // HSET returns error when there's a mismatch in key/values
+			preset:           false,
+			key:              "key7",
+			presetValue:      nil,
+			command:          []string{"HSET", "key7", "field1", "value1", "field2"},
+			expectedResponse: 0,
+			expectedValue:    map[string]interface{}{},
+			expectedError:    errors.New("each field must have a corresponding value"),
+		},
+		{ // Command too short
+			preset:           true,
+			key:              "key8",
+			presetValue:      nil,
+			command:          []string{"HSET", "field1"},
+			expectedResponse: 0,
+			expectedValue:    map[string]interface{}{},
+			expectedError:    errors.New(utils.WRONG_ARGS_RESPONSE),
+		},
+	}
+
+	for _, test := range tests {
+		if test.preset {
+			if _, err := mockServer.CreateKeyAndLock(context.Background(), test.key); err != nil {
+				t.Error(err)
+			}
+			mockServer.SetValue(context.Background(), test.key, test.presetValue)
+			mockServer.KeyUnlock(test.key)
+		}
+		res, err := handleHSET(context.Background(), test.command, mockServer, nil)
+		if test.expectedError != nil {
+			if err.Error() != test.expectedError.Error() {
+				t.Errorf("expected error \"%s\", got \"%s\"", test.expectedError.Error(), err.Error())
+			}
+			continue
+		}
+		rd := resp.NewReader(bytes.NewBuffer(res))
+		rv, _, err := rd.ReadValue()
+		if err != nil {
+			t.Error(err)
+		}
+		if rv.Integer() != test.expectedResponse {
+			t.Errorf("expected response \"%d\", got \"%d\"", test.expectedResponse, rv.Integer())
+		}
+		// Check that all the values are what is expected
+		if _, err = mockServer.KeyRLock(context.Background(), test.key); err != nil {
+			t.Error(err)
+		}
+		hash, ok := mockServer.GetValue(test.key).(map[string]interface{})
+		if !ok {
+			t.Errorf("value at key \"%s\" is not a hash map", test.key)
+		}
+		for field, value := range hash {
+			if value != test.expectedValue[field] {
+				t.Errorf("expected value \"%+v\" for field \"%+v\", got \"%+v\"", test.expectedValue[field], field, value)
+			}
+		}
+	}
 }
 
 func Test_HandleHINCRBY(t *testing.T) {
-	// TODO: test HINCRBY and HINCRBYFLOAT
+	// Tests for both HINCRBY and HINCRBYFLOAT
 }
 
 func Test_HandleHGET(t *testing.T) {}