Fix: Handle empty helmBinary in base files with environment values (#2237)

* Initial plan

* Fix: Default to "helm" when st.DefaultHelmBinary is empty in getHelm()

Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: yxxhero <11087727+yxxhero@users.noreply.github.com>

pkg/app/app.go

@@ -793,6 +793,9 @@ func (a *App) getHelm(st *state.HelmState) (helmexec.Interface, error) {
 	}
 
 	bin := st.DefaultHelmBinary
+	if bin == "" {
+		bin = state.DefaultHelmBinary
+	}
 	kubeconfig := a.Kubeconfig
 	kubectx := st.HelmDefaults.KubeContext
 

pkg/app/app_gethelm_test.go

@@ -0,0 +1,51 @@
+package app
+
+import (
+	goContext "context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/helmfile/helmfile/pkg/state"
+)
+
+// TestGetHelmWithEmptyDefaultHelmBinary tests that getHelm properly defaults to "helm"
+// when st.DefaultHelmBinary is empty. This addresses the issue where base files with
+// environment secrets would fail with "exec: no command" error.
+//
+// Background: When a base file has environment secrets but doesn't specify helmBinary,
+// the state.DefaultHelmBinary would be empty, causing helmexec.New to be called with
+// an empty string, which results in "error determining helm version: exec: no command".
+//
+// The fix in app.getHelm() ensures that when st.DefaultHelmBinary is empty, it defaults
+// to state.DefaultHelmBinary ("helm").
+func TestGetHelmWithEmptyDefaultHelmBinary(t *testing.T) {
+	// Test that app.getHelm() handles empty DefaultHelmBinary correctly by applying a default
+	st := &state.HelmState{
+		ReleaseSetSpec: state.ReleaseSetSpec{
+			DefaultHelmBinary: "", // Empty, as would be the case for base files
+		},
+	}
+
+	logger := newAppTestLogger()
+	app := &App{
+		OverrideHelmBinary:  "",
+		OverrideKubeContext: "",
+		Logger:              logger,
+		Env:                 "default",
+		ctx:                 goContext.Background(),
+	}
+
+	// This should NOT fail because app.getHelm() defaults empty DefaultHelmBinary to "helm"
+	helm, err := app.getHelm(st)
+
+	// Verify that no error occurred - the fix in app.getHelm() prevents the "exec: no command" error
+	require.NoError(t, err, "getHelm should not fail when DefaultHelmBinary is empty (fix should apply default)")
+
+	// Verify that a valid helm execer was returned
+	require.NotNil(t, helm, "getHelm should return a valid helm execer")
+
+	// Verify that the helm version is accessible (confirms the helm binary is valid)
+	version := helm.GetVersion()
+	require.NotNil(t, version, "helm version should be accessible")
+}