[dmt] update copyright year and add no_lang_key tests

pkg/linters/docs/rules/no_lang_key.go

@@ -1,4 +1,4 @@
-// Copyright 2025 Flant JSC
+// Copyright 2026 Flant JSC
 // Licensed under the Apache License, Version 2.0
 
 package rules

pkg/linters/docs/rules/no_lang_key_test.go

@@ -0,0 +1,324 @@
+/*
+Copyright 2026 Flant JSC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rules
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/gojuno/minimock/v3"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/deckhouse/dmt/internal/mocks"
+	"github.com/deckhouse/dmt/pkg"
+	"github.com/deckhouse/dmt/pkg/errors"
+)
+
+func TestNewNoLangKeyRule(t *testing.T) {
+	rule := NewNoLangKeyRule()
+	assert.Equal(t, NoLangKeyRuleName, rule.GetName())
+	assert.Equal(t, "no-lang-key", rule.GetName())
+}
+
+func TestExtractFrontMatter(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+		want    string
+	}{
+		{
+			name:    "valid front matter",
+			content: "---\ntitle: Test\nlang: ru\n---\nBody text",
+			want:    "title: Test\nlang: ru",
+		},
+		{
+			name:    "no front matter at all",
+			content: "Just some text\nwithout front matter",
+			want:    "",
+		},
+		{
+			name:    "only opening delimiter",
+			content: "---\ntitle: Test\nlang: ru",
+			want:    "",
+		},
+		{
+			name:    "empty front matter",
+			content: "---\n---\nBody text",
+			want:    "",
+		},
+		{
+			name:    "delimiter with trailing spaces",
+			content: "---   \ntitle: Test\n---   \nBody text",
+			want:    "title: Test",
+		},
+		{
+			name:    "content after front matter is not included",
+			content: "---\nkey: value\n---\nlang: ru\nMore body text",
+			want:    "key: value",
+		},
+		{
+			name:    "multiple delimiters only first pair used",
+			content: "---\nfirst: block\n---\n---\nsecond: block\n---",
+			want:    "first: block",
+		},
+		{
+			name:    "empty content",
+			content: "",
+			want:    "",
+		},
+		{
+			name:    "single delimiter line",
+			content: "---",
+			want:    "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := extractFrontMatter(tt.content)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func TestFindLangKeyLine(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+		want    int
+	}{
+		{
+			name:    "lang on line 2",
+			content: "---\nlang: ru\n---",
+			want:    2,
+		},
+		{
+			name:    "lang on line 3",
+			content: "---\ntitle: Test\nlang: en\n---",
+			want:    3,
+		},
+		{
+			name:    "no lang key",
+			content: "---\ntitle: Test\n---",
+			want:    0,
+		},
+		{
+			name:    "language key is not lang",
+			content: "---\nlanguage: ru\n---",
+			want:    0,
+		},
+		{
+			name:    "lang without trailing space does not match",
+			content: "---\nlang:ru\n---",
+			want:    0,
+		},
+		{
+			name:    "lang with multiple spaces",
+			content: "---\nlang:   en\n---",
+			want:    2,
+		},
+		{
+			name:    "lang with tab",
+			content: "---\nlang:\tru\n---",
+			want:    2,
+		},
+		{
+			name:    "indented lang key does not match",
+			content: "---\n  lang: ru\n---",
+			want:    0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := findLangKeyLine(tt.content)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func TestNoLangKeyRule_CheckFiles(t *testing.T) {
+	tests := []struct {
+		name       string
+		files      map[string]string // relative to module root
+		wantErrors int
+		wantTexts  []string
+	}{
+		{
+			name: "file without front matter - no errors",
+			files: map[string]string{
+				"docs/README.md": "# Hello\nJust text without front matter",
+			},
+			wantErrors: 0,
+		},
+		{
+			name: "file with front matter but no lang key - no errors",
+			files: map[string]string{
+				"docs/CONFIGURATION.md": "---\ntitle: Configuration\n---\nSome content",
+			},
+			wantErrors: 0,
+		},
+		{
+			name: "file with lang ru in front matter - error",
+			files: map[string]string{
+				"docs/CONFIGURATION.md": "---\ntitle: Test\nlang: ru\n---\nContent",
+			},
+			wantErrors: 1,
+			wantTexts:  []string{"'lang' key"},
+		},
+		{
+			name: "file with lang en in front matter - error",
+			files: map[string]string{
+				"docs/README.md": "---\nlang: en\ntitle: Test\n---\nContent",
+			},
+			wantErrors: 1,
+			wantTexts:  []string{"'lang' key"},
+		},
+		{
+			name: "file in subdirectory docs/sub/ is skipped",
+			files: map[string]string{
+				"docs/sub/NESTED.md": "---\nlang: ru\n---\nContent",
+			},
+			wantErrors: 0,
+		},
+		{
+			name: "multiple files - only those with lang key produce errors",
+			files: map[string]string{
+				"docs/GOOD.md":     "---\ntitle: Good\n---\nContent",
+				"docs/BAD.md":      "---\nlang: ru\ntitle: Bad\n---\nContent",
+				"docs/ALSO_BAD.md": "---\nlang: en\n---\nContent",
+			},
+			wantErrors: 2,
+			wantTexts:  []string{"'lang' key", "'lang' key"},
+		},
+		{
+			name: "non-md file in docs is ignored",
+			files: map[string]string{
+				"docs/image.png": "binary content",
+			},
+			wantErrors: 0,
+		},
+		{
+			name: "lang key outside front matter is not detected",
+			files: map[string]string{
+				"docs/SAFE.md": "---\ntitle: Safe\n---\nlang: ru\nBody text with lang key",
+			},
+			wantErrors: 0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mc := minimock.NewController(t)
+			mockModule := mocks.NewModuleMock(mc)
+
+			tempDir := t.TempDir()
+			mockModule.GetPathMock.Return(tempDir)
+
+			for relPath, content := range tt.files {
+				fullPath := filepath.Join(tempDir, relPath)
+				require.NoError(t, os.MkdirAll(filepath.Dir(fullPath), 0o755))
+				require.NoError(t, os.WriteFile(fullPath, []byte(content), 0o600))
+			}
+
+			rule := NewNoLangKeyRule()
+			errorList := errors.NewLintRuleErrorsList()
+
+			rule.CheckFiles(mockModule, errorList)
+
+			errs := errorList.GetErrors()
+			assert.Len(t, errs, tt.wantErrors)
+
+			for i, wantText := range tt.wantTexts {
+				if i < len(errs) {
+					assert.Contains(t, errs[i].Text, wantText)
+				}
+			}
+		})
+	}
+}
+
+func TestNoLangKeyRule_CheckFiles_EmptyModulePath(t *testing.T) {
+	mc := minimock.NewController(t)
+	mockModule := mocks.NewModuleMock(mc)
+	mockModule.GetPathMock.Return("")
+
+	rule := NewNoLangKeyRule()
+	errorList := errors.NewLintRuleErrorsList()
+
+	rule.CheckFiles(mockModule, errorList)
+
+	errs := errorList.GetErrors()
+	assert.Empty(t, errs)
+}
+
+func TestNoLangKeyRule_CheckFiles_Excluded(t *testing.T) {
+	mc := minimock.NewController(t)
+	mockModule := mocks.NewModuleMock(mc)
+
+	tempDir := t.TempDir()
+	mockModule.GetPathMock.Return(tempDir)
+
+	// Create a file with lang: key in front matter
+	docsDir := filepath.Join(tempDir, "docs")
+	require.NoError(t, os.MkdirAll(docsDir, 0o755))
+	require.NoError(t, os.WriteFile(
+		filepath.Join(docsDir, "EXCLUDED.md"),
+		[]byte("---\nlang: ru\ntitle: Excluded\n---\nContent"),
+		0o600,
+	))
+
+	rule := NewNoLangKeyRule()
+	rule.ExcludeStringRules = []pkg.StringRuleExclude{
+		pkg.StringRuleExclude("docs/EXCLUDED.md"),
+	}
+	errorList := errors.NewLintRuleErrorsList()
+
+	rule.CheckFiles(mockModule, errorList)
+
+	errs := errorList.GetErrors()
+	assert.Empty(t, errs, "Expected excluded file to produce no errors")
+}
+
+func TestNoLangKeyRule_CheckFiles_ErrorLineNumber(t *testing.T) {
+	mc := minimock.NewController(t)
+	mockModule := mocks.NewModuleMock(mc)
+
+	tempDir := t.TempDir()
+	mockModule.GetPathMock.Return(tempDir)
+
+	docsDir := filepath.Join(tempDir, "docs")
+	require.NoError(t, os.MkdirAll(docsDir, 0o755))
+	require.NoError(t, os.WriteFile(
+		filepath.Join(docsDir, "TEST.md"),
+		[]byte("---\ntitle: Test\nlang: ru\nweight: 10\n---\nContent"),
+		0o600,
+	))
+
+	rule := NewNoLangKeyRule()
+	errorList := errors.NewLintRuleErrorsList()
+
+	rule.CheckFiles(mockModule, errorList)
+
+	errs := errorList.GetErrors()
+	require.Len(t, errs, 1)
+	assert.Contains(t, errs[0].Text, "'lang' key")
+	// The value should contain the line number information
+	assert.Contains(t, errs[0].ObjectValue.(string), "Line 3")
+}