diff --git a/codegen/generate_test.go b/codegen/generate_test.go
new file mode 100644
index 00000000..d9d63fbf
--- /dev/null
+++ b/codegen/generate_test.go
@@ -0,0 +1,106 @@
+package main
+
+import (
+	"flag"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/getkin/kin-openapi/openapi3"
+	"github.com/heygen-com/heygen-cli/internal/command"
+)
+
+var update = flag.Bool("update", false, "update golden files")
+
+func loadTestSpec(t *testing.T, path string) *openapi3.T {
+	t.Helper()
+	doc, err := openapi3.NewLoader().LoadFromFile(path)
+	if err != nil {
+		t.Fatalf("failed to load spec %s: %v", path, err)
+	}
+	return doc
+}
+
+func TestGoldenFiles(t *testing.T) {
+	doc := loadTestSpec(t, "testdata/mini_spec.json")
+
+	examples, err := LoadExamples("testdata/test_examples.yaml")
+	if err != nil {
+		t.Fatalf("LoadExamples failed: %v", err)
+	}
+
+	groups, err := GroupEndpoints(doc, examples)
+	if err != nil {
+		t.Fatalf("GroupEndpoints: %v", err)
+	}
+
+	if len(groups) == 0 {
+		t.Fatal("expected at least one command group")
+	}
+
+	outDir := t.TempDir()
+	if err := Generate(groups, "templates", outDir); err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	goldenDir := "testdata/golden"
+
+	if *update {
+		if err := os.MkdirAll(goldenDir, 0755); err != nil {
+			t.Fatalf("creating golden dir: %v", err)
+		}
+		entries, err := os.ReadDir(outDir)
+		if err != nil {
+			t.Fatalf("reading output dir: %v", err)
+		}
+		for _, e := range entries {
+			if e.IsDir() {
+				continue
+			}
+			content, err := os.ReadFile(filepath.Join(outDir, e.Name()))
+			if err != nil {
+				t.Fatalf("reading %s: %v", e.Name(), err)
+			}
+			if err := os.WriteFile(filepath.Join(goldenDir, e.Name()), content, 0644); err != nil {
+				t.Fatalf("writing golden %s: %v", e.Name(), err)
+			}
+		}
+		t.Log("Golden files updated")
+		return
+	}
+
+	goldenEntries, err := os.ReadDir(goldenDir)
+	if err != nil {
+		t.Fatalf("reading golden dir: %v", err)
+	}
+
+	for _, e := range goldenEntries {
+		if e.IsDir() {
+			continue
+		}
+		t.Run(e.Name(), func(t *testing.T) {
+			golden, err := os.ReadFile(filepath.Join(goldenDir, e.Name()))
+			if err != nil {
+				t.Fatalf("reading golden file: %v", err)
+			}
+			actual, err := os.ReadFile(filepath.Join(outDir, e.Name()))
+			if err != nil {
+				t.Fatalf("reading generated file %s: %v", e.Name(), err)
+			}
+			if string(golden) != string(actual) {
+				t.Errorf("output mismatch for %s\nRun with -update to refresh golden files", e.Name())
+			}
+		})
+	}
+}
+
+func TestValidateExamplesMissing(t *testing.T) {
+	groups := command.Groups{
+		"test": {{Method: "GET", Endpoint: "/v3/test"}},
+	}
+
+	err := validateExamples(groups)
+	if err == nil {
+		t.Error("expected error for missing examples")
+	}
+}
diff --git a/codegen/testdata/golden/registry.go b/codegen/testdata/golden/registry.go
new file mode 100644
index 00000000..13e83646
--- /dev/null
+++ b/codegen/testdata/golden/registry.go
@@ -0,0 +1,22 @@
+// Code generated by heygen-cli/codegen. DO NOT EDIT.
+
+package gen
+
+import "github.com/heygen-com/heygen-cli/internal/command"
+
+func intPtr(v int) *int { return &v }
+
+// Groups maps group name → slice of command specs.
+// Used by the command builder to register generated commands.
+var Groups = map[string][]*command.Spec{
+	"upload": {
+		UploadCreate,
+	},
+	"widget": {
+		WidgetActivateCreate,
+		WidgetCreate,
+		WidgetDelete,
+		WidgetGet,
+		WidgetList,
+	},
+}
diff --git a/codegen/testdata/golden/upload.go b/codegen/testdata/golden/upload.go
new file mode 100644
index 00000000..dbe64fc8
--- /dev/null
+++ b/codegen/testdata/golden/upload.go
@@ -0,0 +1,30 @@
+// Code generated by heygen-cli/codegen. DO NOT EDIT.
+
+package gen
+
+import "github.com/heygen-com/heygen-cli/internal/command"
+
+var UploadCreate = &command.Spec{
+	Group:        "upload",
+	Name:         "create",
+	Summary:      "Upload a file",
+	Description:  "",
+	Endpoint:     "/v3/uploads",
+	Method:       "POST",
+	BodyEncoding: "multipart",
+	DataField:    "data",
+	Flags: []command.FlagSpec{
+		{
+			Name:     "file",
+			Type:     "string",
+			Default:  "",
+			Help:     "File to upload",
+			Required: true,
+			Enum:     nil,
+			Min:      nil,
+			Max:      nil,
+			Source:   "file",
+			JSONName: "file",
+		},
+	},
+}
diff --git a/codegen/testdata/golden/widget.go b/codegen/testdata/golden/widget.go
new file mode 100644
index 00000000..f67cf274
--- /dev/null
+++ b/codegen/testdata/golden/widget.go
@@ -0,0 +1,160 @@
+// Code generated by heygen-cli/codegen. DO NOT EDIT.
+
+package gen
+
+import "github.com/heygen-com/heygen-cli/internal/command"
+
+var WidgetActivateCreate = &command.Spec{
+	Group:        "widget",
+	Name:         "activate create",
+	Summary:      "Activate a widget",
+	Description:  "",
+	Endpoint:     "/v3/widgets/{widget_id}/activate",
+	Method:       "POST",
+	BodyEncoding: "json",
+	DataField:    "data",
+	Args: []command.ArgSpec{
+		{Name: "widget-id", Param: "widget_id", Help: ""},
+	},
+	Flags: []command.FlagSpec{
+		{
+			Name:     "force",
+			Type:     "bool",
+			Default:  "false",
+			Help:     "Force activation",
+			Required: false,
+			Enum:     nil,
+			Min:      nil,
+			Max:      nil,
+			Source:   "body",
+			JSONName: "force",
+		},
+	},
+}
+
+var WidgetCreate = &command.Spec{
+	Group:        "widget",
+	Name:         "create",
+	Summary:      "Create a widget",
+	Description:  "",
+	Endpoint:     "/v3/widgets",
+	Method:       "POST",
+	BodyEncoding: "json",
+	DataField:    "data",
+	Flags: []command.FlagSpec{
+		{
+			Name:     "count",
+			Type:     "int",
+			Default:  "",
+			Help:     "Widget count",
+			Required: false,
+			Enum:     nil,
+			Min:      intPtr(1),
+			Max:      intPtr(100),
+			Source:   "body",
+			JSONName: "count",
+		},
+		{
+			Name:     "name",
+			Type:     "string",
+			Default:  "",
+			Help:     "Widget name",
+			Required: true,
+			Enum:     nil,
+			Min:      nil,
+			Max:      nil,
+			Source:   "body",
+			JSONName: "name",
+		},
+		{
+			Name:     "tags",
+			Type:     "string-slice",
+			Default:  "",
+			Help:     "Widget tags",
+			Required: false,
+			Enum:     nil,
+			Min:      nil,
+			Max:      nil,
+			Source:   "body",
+			JSONName: "tags",
+		},
+	},
+}
+
+var WidgetDelete = &command.Spec{
+	Group:        "widget",
+	Name:         "delete",
+	Summary:      "Delete a widget",
+	Description:  "",
+	Endpoint:     "/v3/widgets/{widget_id}",
+	Method:       "DELETE",
+	BodyEncoding: "",
+	DataField:    "data",
+	Args: []command.ArgSpec{
+		{Name: "widget-id", Param: "widget_id", Help: ""},
+	},
+}
+
+var WidgetGet = &command.Spec{
+	Group:        "widget",
+	Name:         "get",
+	Summary:      "Get widget details",
+	Description:  "",
+	Endpoint:     "/v3/widgets/{widget_id}",
+	Method:       "GET",
+	BodyEncoding: "",
+	DataField:    "data",
+	Args: []command.ArgSpec{
+		{Name: "widget-id", Param: "widget_id", Help: ""},
+	},
+}
+
+var WidgetList = &command.Spec{
+	Group:        "widget",
+	Name:         "list",
+	Summary:      "List widgets",
+	Description:  "",
+	Endpoint:     "/v3/widgets",
+	Method:       "GET",
+	BodyEncoding: "",
+	TokenField:   "next_token",
+	DataField:    "data",
+	Flags: []command.FlagSpec{
+		{
+			Name:     "limit",
+			Type:     "int",
+			Default:  "10",
+			Help:     "Max results per page",
+			Required: false,
+			Enum:     nil,
+			Min:      intPtr(1),
+			Max:      intPtr(100),
+			Source:   "query",
+			JSONName: "limit",
+		},
+		{
+			Name:     "token",
+			Type:     "string",
+			Default:  "",
+			Help:     "Pagination token",
+			Required: false,
+			Enum:     nil,
+			Min:      nil,
+			Max:      nil,
+			Source:   "query",
+			JSONName: "token",
+		},
+		{
+			Name:     "status",
+			Type:     "string",
+			Default:  "",
+			Help:     "Filter by status",
+			Required: false,
+			Enum:     []string{"active", "archived"},
+			Min:      nil,
+			Max:      nil,
+			Source:   "query",
+			JSONName: "status",
+		},
+	},
+}
diff --git a/codegen/testdata/mini_spec.json b/codegen/testdata/mini_spec.json
new file mode 100644
index 00000000..64895f26
--- /dev/null
+++ b/codegen/testdata/mini_spec.json
@@ -0,0 +1,330 @@
+{
+  "openapi": "3.0.0",
+  "info": {
+    "title": "Mini Test API",
+    "version": "1.0.0"
+  },
+  "paths": {
+    "/v3/widgets": {
+      "get": {
+        "tags": ["Widgets"],
+        "summary": "List widgets",
+        "operationId": "listWidgets",
+        "parameters": [
+          {
+            "name": "limit",
+            "in": "query",
+            "required": false,
+            "schema": {
+              "type": "integer",
+              "minimum": 1,
+              "maximum": 100,
+              "default": 10
+            },
+            "description": "Max results per page"
+          },
+          {
+            "name": "token",
+            "in": "query",
+            "required": false,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Pagination token"
+          },
+          {
+            "name": "status",
+            "in": "query",
+            "required": false,
+            "schema": {
+              "type": "string",
+              "enum": ["active", "archived"]
+            },
+            "description": "Filter by status"
+          }
+        ],
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "data": {
+                      "type": "array",
+                      "items": {
+                        "type": "object"
+                      }
+                    },
+                    "has_more": {
+                      "type": "boolean"
+                    },
+                    "next_token": {
+                      "type": ["string", "null"]
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      },
+      "post": {
+        "tags": ["Widgets"],
+        "summary": "Create a widget",
+        "operationId": "createWidget",
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/CreateWidgetRequest"
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "data": {
+                      "$ref": "#/components/schemas/Widget"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "/v3/widgets/{widget_id}": {
+      "get": {
+        "tags": ["Widgets"],
+        "summary": "Get widget details",
+        "operationId": "getWidget",
+        "parameters": [
+          {
+            "name": "widget_id",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Widget ID"
+          }
+        ],
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "data": {
+                      "$ref": "#/components/schemas/Widget"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      },
+      "delete": {
+        "tags": ["Widgets"],
+        "summary": "Delete a widget",
+        "operationId": "deleteWidget",
+        "parameters": [
+          {
+            "name": "widget_id",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Widget ID"
+          }
+        ],
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "data": {
+                      "type": "object"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "/v3/widgets/{widget_id}/activate": {
+      "post": {
+        "tags": ["Widgets"],
+        "summary": "Activate a widget",
+        "operationId": "activateWidget",
+        "parameters": [
+          {
+            "name": "widget_id",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string"
+            },
+            "description": "Widget ID"
+          }
+        ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/ActivateWidgetRequest"
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "data": {
+                      "type": "object"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "/v3/uploads": {
+      "post": {
+        "tags": ["Uploads"],
+        "summary": "Upload a file",
+        "operationId": "uploadFile",
+        "requestBody": {
+          "content": {
+            "multipart/form-data": {
+              "schema": {
+                "type": "object",
+                "properties": {
+                  "file": {
+                    "type": "string",
+                    "format": "binary",
+                    "description": "File to upload"
+                  }
+                },
+                "required": ["file"]
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object",
+                  "properties": {
+                    "data": {
+                      "type": "object"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    },
+    "/v1/legacy": {
+      "get": {
+        "tags": ["Legacy"],
+        "summary": "Legacy endpoint (should be skipped)",
+        "operationId": "legacyGet",
+        "x-cli-visible": false,
+        "responses": {
+          "200": {
+            "content": {
+              "application/json": {
+                "schema": {
+                  "type": "object"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "schemas": {
+      "Widget": {
+        "type": "object",
+        "properties": {
+          "id": {"type": "string"},
+          "name": {"type": "string"},
+          "status": {"type": "string"}
+        }
+      },
+      "CreateWidgetRequest": {
+        "type": "object",
+        "properties": {
+          "name": {
+            "type": "string",
+            "description": "Widget name"
+          },
+          "color": {
+            "anyOf": [
+              {"type": "string"},
+              {"type": "null"}
+            ],
+            "default": null,
+            "description": "Widget color"
+          },
+          "count": {
+            "type": "integer",
+            "description": "Widget count",
+            "minimum": 1,
+            "maximum": 100
+          },
+          "tags": {
+            "type": "array",
+            "items": {"type": "string"},
+            "description": "Widget tags"
+          },
+          "settings": {
+            "type": "object",
+            "description": "Complex settings object",
+            "properties": {
+              "nested": {"type": "string"}
+            }
+          }
+        },
+        "required": ["name"]
+      },
+      "ActivateWidgetRequest": {
+        "type": "object",
+        "properties": {
+          "force": {
+            "type": "boolean",
+            "description": "Force activation",
+            "default": false
+          }
+        }
+      }
+    }
+  }
+}