Add helmfile state validate policy (#592)

pkg/policy/checker.go

@@ -0,0 +1,37 @@
+// Package policy provides a policy checker for the helmfile state.
+package policy
+
+import (
+	"errors"
+)
+
+var (
+	EnvironmentsAndReleasesWithinSameYamlPartErr = errors.New("environments and releases cannot be defined within the same YAML part. Use --- to extract the environments into a dedicated part")
+)
+
+// checkerFunc is a function that checks the helmState.
+type checkerFunc func(map[string]interface{}) (bool, error)
+
+func forbidEnvironmentsWithReleases(releaseState map[string]interface{}) (bool, error) {
+	// forbid environments and releases to be defined at the same yaml part
+	_, hasEnvironments := releaseState["environments"]
+	_, hasReleases := releaseState["releases"]
+	if hasEnvironments && hasReleases {
+		return false, EnvironmentsAndReleasesWithinSameYamlPartErr
+	}
+	return false, nil
+}
+
+var checkerFuncs = []checkerFunc{
+	forbidEnvironmentsWithReleases,
+}
+
+// Checker is a policy checker for the helmfile state.
+func Checker(helmState map[string]interface{}) (bool, error) {
+	for _, fn := range checkerFuncs {
+		if isStrict, err := fn(helmState); err != nil {
+			return isStrict, err
+		}
+	}
+	return false, nil
+}

pkg/policy/checker_test.go

@@ -0,0 +1,54 @@
+package policy
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestForbidEnvironmentsWithReleases(t *testing.T) {
+	testCases := []struct {
+		name        string
+		helmState   map[string]interface{}
+		expectedErr bool
+		isStrict    bool
+	}{
+		{
+			name: "no error when only releases",
+			helmState: map[string]interface{}{
+				"releases": interface{}(nil),
+			},
+			expectedErr: false,
+			isStrict:    false,
+		},
+		{
+			name: "no error when only environments",
+			helmState: map[string]interface{}{
+				"environments": map[string]interface{}{},
+			},
+			expectedErr: false,
+			isStrict:    false,
+		},
+		{
+			name: "error when both releases and environments",
+			helmState: map[string]interface{}{
+				"environments": interface{}(nil),
+				"releases":     interface{}(nil),
+			},
+			expectedErr: true,
+			isStrict:    false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			isStrict, err := forbidEnvironmentsWithReleases(tc.helmState)
+			require.Equal(t, tc.isStrict, isStrict, "expected isStrict=%v, got=%v", tc.isStrict, isStrict)
+			if tc.expectedErr {
+				require.ErrorIsf(t, err, EnvironmentsAndReleasesWithinSameYamlPartErr, "expected error=%v, got=%v", EnvironmentsAndReleasesWithinSameYamlPartErr, err)
+			} else {
+				require.NoError(t, err, "expected no error but got error: %v", err)
+			}
+		})
+	}
+}