NPM packages: Fail `build-frontend-packages` step if `package.json` and input tag differ (#70011)

* Fail if package.json version is different than the tag

* Add tests

* Update message

* Small refactoring

* Fix lint

pkg/build/frontend/config.go

@@ -1,31 +1,39 @@
 package frontend
 
 import (
-	"github.com/urfave/cli/v2"
+	"fmt"
 
 	"github.com/grafana/grafana/pkg/build/config"
+	"github.com/urfave/cli/v2"
 )
 
 const GrafanaDir = "."
 
-func GetConfig(c *cli.Context, version string) (config.Config, config.Edition, error) {
+func GetConfig(c *cli.Context, inputTagVersion string) (config.Config, config.Edition, error) {
 	cfg := config.Config{
 		NumWorkers:     c.Int("jobs"),
 		GitHubToken:    c.String("github-token"),
-		PackageVersion: version,
+		PackageVersion: inputTagVersion,
 	}
 
 	mode := config.Edition(c.String("edition"))
+	buildID := c.String("build-id")
+	packageVersion, err := config.GetGrafanaVersion(buildID, GrafanaDir)
+	if err != nil {
+		return config.Config{}, "", cli.Exit(err.Error(), 1)
+	}
 
-	if version == "" {
-		buildID := c.String("build-id")
-		var err error
-		version, err = config.GetGrafanaVersion(buildID, GrafanaDir)
-		cfg.PackageVersion = version
+	if inputTagVersion == "" {
+		cfg.PackageVersion = packageVersion
 		if err != nil {
 			return config.Config{}, config.EditionOSS, cli.Exit(err.Error(), 1)
 		}
+		return cfg, mode, err
+	}
+	if inputTagVersion != packageVersion {
+		return config.Config{}, "", cli.Exit(fmt.Errorf("package.json version and input tag version differ %s != %s.\nPlease update package.json", packageVersion, inputTagVersion), 1)
 	}
 
+	cfg.PackageVersion = inputTagVersion
 	return cfg, mode, nil
 }

pkg/build/frontend/config_test.go

@@ -0,0 +1,102 @@
+package frontend
+
+import (
+	"encoding/json"
+	"flag"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/urfave/cli/v2"
+)
+
+const (
+	jobs        = "jobs"
+	githubToken = "github-token"
+)
+
+type packageJson struct {
+	Version string `json:"version"`
+}
+
+var app = cli.NewApp()
+
+func TestGetConfig(t *testing.T) {
+	tests := []struct {
+		ctx                *cli.Context
+		name               string
+		packageJsonVersion string
+		tagVersion         string
+		wantErr            bool
+	}{
+		{
+			ctx:                cli.NewContext(app, setFlags(t, jobs, githubToken, flag.NewFlagSet("flagSet", flag.ContinueOnError)), nil),
+			name:               "package.json matches tag",
+			packageJsonVersion: "10.0.0",
+			tagVersion:         "10.0.0",
+			wantErr:            false,
+		},
+		{
+			ctx:                cli.NewContext(app, setFlags(t, jobs, githubToken, flag.NewFlagSet("flagSet", flag.ContinueOnError)), nil),
+			name:               "package.json doesn't match tag",
+			packageJsonVersion: "10.1.0",
+			tagVersion:         "10.0.0",
+			wantErr:            true,
+		},
+		{
+			ctx:                cli.NewContext(app, setFlags(t, jobs, githubToken, flag.NewFlagSet("flagSet", flag.ContinueOnError)), nil),
+			name:               "non-tag event",
+			packageJsonVersion: "10.1.0",
+			tagVersion:         "",
+			wantErr:            false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var context cli.Context
+			err := createTempPackageJson(t, tt.packageJsonVersion)
+			require.NoError(t, err)
+			defer deleteTempPackageJson(t)
+
+			got, _, err := GetConfig(&context, tt.tagVersion)
+			if !tt.wantErr {
+				require.Equal(t, got.PackageVersion, tt.packageJsonVersion)
+			}
+
+			if tt.wantErr {
+				require.Equal(t, got.PackageVersion, "")
+				require.Error(t, err)
+			}
+		})
+	}
+}
+
+func setFlags(t *testing.T, flag1, flag2 string, flagSet *flag.FlagSet) *flag.FlagSet {
+	t.Helper()
+	if flag1 != "" {
+		flagSet.StringVar(&flag1, jobs, "2", "")
+	}
+	if flag2 != "" {
+		flagSet.StringVar(&flag2, githubToken, "token", "")
+	}
+	return flagSet
+}
+
+func createTempPackageJson(t *testing.T, version string) error {
+	t.Helper()
+
+	data := packageJson{Version: version}
+	file, _ := json.MarshalIndent(data, "", " ")
+
+	err := os.WriteFile("package.json", file, 0644)
+	require.NoError(t, err)
+
+	return nil
+}
+
+func deleteTempPackageJson(t *testing.T) {
+	t.Helper()
+
+	err := os.RemoveAll("package.json")
+	require.NoError(t, err)
+}