Add unit tests for alertspb ToProto and ParseTemplates (#7353)

* Add unit tests for alertspb ToProto and ParseTemplates

Signed-off-by: Artem Muterko <artem@sopho.tech>

* test: fix gofmt alignment in struct fields

Signed-off-by: Artem Muterko <artem@sopho.tech>

---------

Signed-off-by: Artem Muterko <artem@sopho.tech>

Author: archy-rock3t-cloud

pkg/alertmanager/alertspb/compat_test.go

@@ -0,0 +1,118 @@
+package alertspb
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestToProto(t *testing.T) {
+	tests := []struct {
+		name      string
+		cfg       string
+		templates map[string]string
+		user      string
+	}{
+		{
+			name:      "empty config and no templates",
+			cfg:       "",
+			templates: nil,
+			user:      "user-1",
+		},
+		{
+			name: "config with templates",
+			cfg:  "route:\n  receiver: default",
+			templates: map[string]string{
+				"slack.tmpl": "{{ define \"slack\" }}alert{{ end }}",
+			},
+			user: "user-2",
+		},
+		{
+			name:      "empty user",
+			cfg:       "global: {}",
+			templates: nil,
+			user:      "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := ToProto(tt.cfg, tt.templates, tt.user)
+
+			assert.Equal(t, tt.user, result.User)
+			assert.Equal(t, tt.cfg, result.RawConfig)
+
+			if tt.templates == nil {
+				assert.Empty(t, result.Templates)
+			} else {
+				assert.Len(t, result.Templates, len(tt.templates))
+				for _, tmpl := range result.Templates {
+					expectedBody, ok := tt.templates[tmpl.Filename]
+					assert.True(t, ok, "unexpected template filename: %s", tmpl.Filename)
+					assert.Equal(t, expectedBody, tmpl.Body)
+				}
+			}
+		})
+	}
+}
+
+func TestParseTemplates(t *testing.T) {
+	tests := []struct {
+		name     string
+		cfg      AlertConfigDesc
+		expected map[string]string
+	}{
+		{
+			name:     "no templates",
+			cfg:      AlertConfigDesc{Templates: nil},
+			expected: map[string]string{},
+		},
+		{
+			name: "single template",
+			cfg: AlertConfigDesc{
+				Templates: []*TemplateDesc{
+					{Filename: "slack.tmpl", Body: "{{ define \"slack\" }}msg{{ end }}"},
+				},
+			},
+			expected: map[string]string{
+				"slack.tmpl": "{{ define \"slack\" }}msg{{ end }}",
+			},
+		},
+		{
+			name: "multiple templates",
+			cfg: AlertConfigDesc{
+				Templates: []*TemplateDesc{
+					{Filename: "a.tmpl", Body: "body-a"},
+					{Filename: "b.tmpl", Body: "body-b"},
+				},
+			},
+			expected: map[string]string{
+				"a.tmpl": "body-a",
+				"b.tmpl": "body-b",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := ParseTemplates(tt.cfg)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestToProto_ParseTemplates_roundtrip(t *testing.T) {
+	templates := map[string]string{
+		"email.tmpl": "{{ define \"email\" }}hello{{ end }}",
+		"slack.tmpl": "{{ define \"slack\" }}alert{{ end }}",
+	}
+	cfg := "route:\n  receiver: default"
+	user := "test-user"
+
+	proto := ToProto(cfg, templates, user)
+	result := ParseTemplates(proto)
+
+	assert.Equal(t, templates, result)
+	assert.Equal(t, cfg, proto.RawConfig)
+	assert.Equal(t, user, proto.User)
+}