diff --git a/handler/template_test.go b/handler/template_test.go
new file mode 100644
index 0000000..13b7525
--- /dev/null
+++ b/handler/template_test.go
@@ -0,0 +1,192 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+package handler
+
+import (
+	"fmt"
+	"os/exec"
+	"testing"
+	"text/template"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_runTemplate(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		Name        string
+		Template    *template.Template
+		Env         TemplateEnv
+		Expected    string
+		ShouldError bool
+		HandlerFunc func(t *testing.T, expected, actual string) bool
+	}{
+		{
+			Name:     "Empty",
+			Template: s2t(""),
+		},
+		{
+			Name:     "TextOnly",
+			Template: s2t("hello, this is a text only template"),
+			Expected: "hello, this is a text only template",
+		},
+		{
+			Name:     "WithEvent",
+			Template: s2t("{{.Event.Instance}}:{{.Event.State}}:{{.Event.Type}}"),
+			Expected: "foo_instance:MASTER:INSTANCE",
+			Env: TemplateEnv{
+				Event: MessageEvent{
+					Instance: "foo_instance",
+					Type:     "INSTANCE",
+					State:    "MASTER",
+				},
+			},
+		},
+		{
+			Name:     "WithCxt",
+			Template: s2t("{{.Cxt.key1}}:{{.Cxt.key2.subkey1}}:{{.Cxt.UpCase.Key}}"),
+			Expected: "value1:value2:value3",
+			Env: TemplateEnv{
+				Cxt: map[string]any{
+					"key1": "value1",
+					"key2": map[string]string{
+						"subkey1": "value2",
+					},
+					"UpCase": map[string]string{
+						"Key": "value3",
+					},
+				},
+			},
+		},
+		{
+			Name:     "WithCxtAndEvent",
+			Template: s2t("{{.Event.Instance}}->{{.Cxt.key1}}:{{.Cxt.key2.subkey1}}:{{.Cxt.UpCase.Key}}"),
+			Expected: "baz_instance->value1:value2:value3",
+			Env: TemplateEnv{
+				Cxt: map[string]any{
+					"key1": "value1",
+					"key2": map[string]string{
+						"subkey1": "value2",
+					},
+					"UpCase": map[string]string{
+						"Key": "value3",
+					},
+				},
+				Event: MessageEvent{
+					Instance: "baz_instance",
+				},
+			},
+		},
+	}
+
+	for i, test := range cases {
+		test := test // Avoid closure capture by ref
+		tname := fmt.Sprintf("%s@%d:%d", test.Name, i+1, len(cases))
+
+		t.Run(tname, func(t *testing.T) {
+			t.Parallel()
+
+			if test.HandlerFunc == nil {
+				test.HandlerFunc = Noop[string]
+				if test.Expected != "" {
+					test.HandlerFunc = ExpectEqual[string]
+					if test.ShouldError {
+						test.HandlerFunc = ExpectNotEqual[string]
+					}
+				}
+			}
+
+			actual, err := runTemplate(test.Template, &test.Env)
+			if test.ShouldError && err != nil {
+				return
+			} else if assert.NoError(t, err) {
+				test.HandlerFunc(t, test.Expected, actual)
+			}
+		})
+	}
+}
+
+func Test_mkCmd(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		Name        string
+		Cmdline     string
+		Expected    *exec.Cmd
+		ShouldError bool
+		HandlerFunc func(t *testing.T, expected, actual *exec.Cmd) bool
+	}{
+		{
+			Name:        "Empty",
+			Cmdline:     "",
+			ShouldError: true,
+		},
+		{
+			Name:     "CmdOnly",
+			Cmdline:  "/bin/echo",
+			Expected: exec.Command("/bin/echo"),
+		},
+		{
+			Name:     "WithArgsSimple",
+			Cmdline:  "/bin/echo hello, world!",
+			Expected: exec.Command("/bin/echo", "hello,", "world!"),
+		},
+		{
+			Name:     "WithArgsEscape",
+			Cmdline:  `/bin/echo \$ESCAPED $VAR`,
+			Expected: exec.Command("/bin/echo", `$ESCAPED`, "$VAR"),
+		},
+		{
+			Name:     "WithArgsQuoted",
+			Cmdline:  `/bin/echo "hello, world" ... 'these have spaces'`,
+			Expected: exec.Command("/bin/echo", "hello, world", "...", "these have spaces"),
+		},
+	}
+
+	for i, test := range cases {
+		test := test // Avoid closure capture by ref
+		tname := fmt.Sprintf("%s@%d:%d", test.Name, i+1, len(cases))
+
+		t.Run(tname, func(t *testing.T) {
+			t.Parallel()
+
+			if test.HandlerFunc == nil {
+				test.HandlerFunc = Noop[*exec.Cmd]
+				if test.Expected != nil {
+					test.HandlerFunc = ExpectEqual[*exec.Cmd]
+					if test.ShouldError {
+						test.HandlerFunc = ExpectNotEqual[*exec.Cmd]
+					}
+				}
+			}
+
+			actual, err := mkCmd(test.Cmdline)
+			if test.ShouldError && err != nil {
+				return
+			} else if assert.NoError(t, err) {
+				test.HandlerFunc(t, test.Expected, actual)
+			}
+		})
+	}
+}
+
+func ExpectEqual[T any](t *testing.T, expected, actual T) bool {
+	return assert.Equal(t, expected, actual)
+}
+
+func ExpectNotEqual[T any](t *testing.T, expected, actual T) bool {
+	return assert.NotEqual(t, expected, actual)
+}
+
+func Noop[T any](_ *testing.T, _, _ T) bool {
+	return true
+}
+
+func s2t(s string) *template.Template {
+	return template.Must(template.New("TestHandler").Parse(s))
+}