diff --git a/pkg/template/fill_test.go b/pkg/template/fill_test.go
new file mode 100644
index 0000000000..86c589e56d
--- /dev/null
+++ b/pkg/template/fill_test.go
@@ -0,0 +1,108 @@
+package template
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"gotest.tools/assert"
+)
+
+func TestFillTemplate(t *testing.T) {
+	cases := []struct {
+		name     string
+		tmpl     string
+		vars     map[string]string
+		want     string
+		wantErr  bool
+		errMatch string
+	}{
+		{
+			name: "simple substitution",
+			tmpl: "hello {{.Name}}",
+			vars: map[string]string{"Name": "devsy"},
+			want: "hello devsy",
+		},
+		{
+			name: "multiple vars",
+			tmpl: "{{.First}}-{{.Second}}",
+			vars: map[string]string{"First": "a", "Second": "b"},
+			want: "a-b",
+		},
+		{
+			name: "repeated var reused",
+			tmpl: "{{.Tag}} and {{.Tag}}",
+			vars: map[string]string{"Tag": "x"},
+			want: "x and x",
+		},
+		{
+			name: "no vars passes through unchanged",
+			tmpl: "plain text with no placeholders",
+			vars: map[string]string{},
+			want: "plain text with no placeholders",
+		},
+		{
+			name: "missing var renders no-value sentinel",
+			tmpl: "[{{.Missing}}]",
+			vars: map[string]string{"Other": "y"},
+			want: "[<no value>]",
+		},
+		{
+			name:    "unclosed action is a parse error",
+			tmpl:    "hello {{.Name",
+			vars:    map[string]string{"Name": "devsy"},
+			wantErr: true,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := FillTemplate(tc.tmpl, tc.vars)
+			if tc.wantErr {
+				assert.ErrorContains(t, err, tc.errMatch)
+				return
+			}
+			assert.NilError(t, err)
+			assert.Equal(t, tc.want, got)
+		})
+	}
+}
+
+func TestFillTemplateEmpty(t *testing.T) {
+	got, err := FillTemplate("", map[string]string{})
+	assert.NilError(t, err)
+	assert.Equal(t, "", got)
+}
+
+func TestWriteFiles(t *testing.T) {
+	folder := t.TempDir()
+	files := map[string]string{
+		"a.txt": "alpha",
+		"b.txt": "beta content",
+	}
+
+	err := WriteFiles(folder, files)
+	assert.NilError(t, err)
+	for rel, want := range files {
+		path := filepath.Join(folder, rel)
+		got, err := os.ReadFile(path) // #nosec G304 -- test-controlled temp path
+		assert.NilError(t, err)
+		assert.Equal(t, want, string(got))
+
+		info, err := os.Stat(path)
+		assert.NilError(t, err)
+		assert.Equal(t, os.FileMode(0o600), info.Mode().Perm())
+	}
+}
+
+func TestWriteFilesNestedPathFailsWithoutMkdir(t *testing.T) {
+	folder := t.TempDir()
+	err := WriteFiles(folder, map[string]string{"sub/a.txt": "nested content"})
+	assert.ErrorContains(t, err, "no such file or directory")
+}
+
+func TestWriteFilesErrorOnMissingFolder(t *testing.T) {
+	missing := filepath.Join(t.TempDir(), "does", "not", "exist")
+	err := WriteFiles(missing, map[string]string{"a.txt": "orphan content"})
+	assert.ErrorContains(t, err, "no such file or directory")
+}