initial commit and release
This commit is contained in:
commit
a8a93ab5ae
218
hrender.go
Normal file
218
hrender.go
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@ -0,0 +1,218 @@
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package main
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import (
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"bytes"
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"fmt"
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"html/template"
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"io/fs"
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"log/slog"
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"net/http"
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"path/filepath"
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"strings"
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"sync"
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)
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type (
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H map[string]any
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HRender struct {
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fs fs.FS
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enableCache bool
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funcMap template.FuncMap
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cache map[string]*template.Template
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cacheMu sync.RWMutex
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}
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)
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// NewHTMLRender initializes a new Render instance.
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// fileSystem: The file system containing the templates (usually embed.FS or os.DirFS).
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// enableCache: If true, templates will be compiled once and cached for future use.
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func NewHTMLRender(fileSystem fs.FS, enableCache bool) *HRender {
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return &HRender{
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fs: fileSystem,
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enableCache: enableCache,
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cache: make(map[string]*template.Template),
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funcMap: template.FuncMap{
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"dict": Dict,
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},
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}
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}
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// AddFunc registers a custom function to the template's FuncMap.
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// This must be called before rendering any templates if you want the function to be available.
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func (r *HRender) AddFunc(name string, fn any) {
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r.funcMap[name] = fn
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}
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// Render executes the template for the given pageName and writes the result to w.
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// pageName: The path to the page template (e.g., "pages/login.html").
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// data: The data map to be passed to the template.
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// layoutName: (Optional) The path to the layout template (e.g., "layouts/base.html").
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//
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// If caching is enabled, it checks the cache first. If not found (or cache disabled),
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// it compiles the template (merging layout and page) and caches it if appropriate.
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func (r *HRender) Render(w http.ResponseWriter, pageName string, data H, layoutName ...string) error {
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if !strings.HasSuffix(pageName, ".html") {
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pageName += ".html"
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}
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var layout string
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if len(layoutName) > 0 && layoutName[0] != "" {
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layout = layoutName[0]
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if !strings.HasSuffix(layout, ".html") {
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layout += ".html"
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}
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}
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cacheKey := pageName
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if layout != "" {
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cacheKey = layout + "::" + pageName
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}
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var tmpl *template.Template
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var err error
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if r.enableCache {
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r.cacheMu.RLock()
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cachedTmpl, ok := r.cache[cacheKey]
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r.cacheMu.RUnlock()
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if ok {
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return r.execute(w, cachedTmpl, data)
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}
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r.cacheMu.Lock()
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if cachedTmpl, ok = r.cache[cacheKey]; ok {
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r.cacheMu.Unlock()
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return r.execute(w, cachedTmpl, data)
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}
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tmpl, err = r.buildTemplate(pageName, layout)
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if err != nil {
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r.cacheMu.Unlock()
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return err
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}
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r.cache[cacheKey] = tmpl
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slog.Debug("template compiled and cached", "key", cacheKey)
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r.cacheMu.Unlock()
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} else {
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tmpl, err = r.buildTemplate(pageName, layout)
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if err != nil {
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return err
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}
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}
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return r.execute(w, tmpl, data)
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}
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// execute runs the template into a buffer first to catch any execution errors
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// before writing to the response writer. This prevents partial writes on error.
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func (r *HRender) execute(w http.ResponseWriter, tmpl *template.Template, data H) error {
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var buf bytes.Buffer
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if err := tmpl.Execute(&buf, data); err != nil {
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return err
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}
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_, err := buf.WriteTo(w)
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return err
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}
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// buildTemplate constructs a new template instance by:
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// 1. Reading the page content.
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// 2. Reading the layout content (if provided) and embedding the page content into it using {{ embed }}.
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// 3. Walking the file system to parse all other available templates (fragments/components) so they can be invoked.
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func (r *HRender) buildTemplate(pageName, layoutName string) (*template.Template, error) {
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pageContent, err := fs.ReadFile(r.fs, pageName)
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if err != nil {
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return nil, fmt.Errorf("page not found: %w", err)
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}
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var finalContent string
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if layoutName != "" {
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layoutBytes, err := fs.ReadFile(r.fs, layoutName)
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if err != nil {
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return nil, fmt.Errorf("layout not found: %w", err)
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}
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layoutStr := string(layoutBytes)
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layoutStr = strings.ReplaceAll(layoutStr, "{{ embed }}", string(pageContent))
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layoutStr = strings.ReplaceAll(layoutStr, "{{embed}}", string(pageContent))
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finalContent = layoutStr
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} else {
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finalContent = string(pageContent)
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}
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tmpl := template.New("root").Funcs(r.funcMap)
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if _, err := tmpl.Parse(finalContent); err != nil {
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return nil, fmt.Errorf("error parsing main content: %w", err)
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}
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err = fs.WalkDir(r.fs, ".", func(path string, d fs.DirEntry, err error) error {
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if err != nil {
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return err
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}
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if d.IsDir() {
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return nil
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}
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if !strings.HasSuffix(path, ".html") && !strings.HasSuffix(path, ".gohtml") {
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return nil
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}
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if path == pageName || path == layoutName {
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return nil
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}
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content, err := fs.ReadFile(r.fs, path)
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if err != nil {
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return err
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}
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name := filepath.ToSlash(path)
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name = strings.TrimSuffix(name, filepath.Ext(name))
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_, err = tmpl.New(name).Parse(string(content))
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return err
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})
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if err != nil {
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return nil, err
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}
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return tmpl, nil
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}
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// Dict creates a map[string]any from a list of key-value pairs.
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// It expects an even number of arguments, where every odd argument is a string key
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// and the following argument is its value.
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//
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// This is particularly useful for passing multiple pieces of data to a sub-template
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// or fragment, as Go templates normally only accept a single pipeline argument.
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//
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// Usage in template:
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//
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// {{ template "fragments/input" dict "Label" "Username" "Value" .User.Name "Type" "text" }}
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//
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// Returns:
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// - A map[string]any containing the key-value pairs.
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// - A map with an "error" key if the number of arguments is odd or a key is not a string.
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func Dict(values ...any) map[string]any {
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if len(values)%2 != 0 {
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return map[string]any{
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"error": "invalid dict call",
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}
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}
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dict := make(map[string]any, len(values)/2)
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for i := 0; i < len(values); i += 2 {
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key, ok := values[i].(string)
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if !ok {
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return map[string]any{
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"error": "dict keys must be strings",
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}
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}
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dict[key] = values[i+1]
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}
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return dict
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}
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229
hrender_test.go
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229
hrender_test.go
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@ -0,0 +1,229 @@
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package main
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import (
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"bytes"
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"html/template"
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"log/slog"
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"net/http/httptest"
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"reflect"
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"strings"
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"testing"
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"testing/fstest"
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)
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func Test_Render(t *testing.T) {
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tests := []struct {
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name string
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mockFS fstest.MapFS
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data H
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page string
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layout string
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customFuncs template.FuncMap
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expectedError bool
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expectedBody string
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}{
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{
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name: "simple page",
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mockFS: fstest.MapFS{
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"index.html": {
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Data: []byte(`<h1>hello world</h1>`),
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},
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},
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page: "index.html",
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expectedBody: "<h1>hello world</h1>",
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},
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{
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name: "simple page with layout",
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mockFS: fstest.MapFS{
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"index.html": {
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Data: []byte(`<h1>hello world</h1>`),
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},
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"main-layout.html": {
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Data: []byte(`<main>{{ embed }}</main>`),
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},
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},
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page: "index.html",
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layout: "main-layout.html",
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expectedBody: "<main><h1>hello world</h1></main>",
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},
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{
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name: "simple page with fragment",
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mockFS: fstest.MapFS{
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"index.html": {
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Data: []byte(`<h1>{{ template "fragments/header" . }}</h1>`),
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},
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"fragments/header.html": {
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Data: []byte(`Hello Header`),
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},
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},
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page: "index.html",
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expectedBody: "<h1>Hello Header</h1>",
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},
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{
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name: "simple page with layout and fragment",
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mockFS: fstest.MapFS{
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"layout.html": {
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Data: []byte(`<body>{{ embed }}</body>`),
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},
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"index.html": {
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Data: []byte(`<div>{{ template "fragments/footer" . }}</div>`),
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},
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"fragments/footer.html": {
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Data: []byte(`Footer Content`),
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},
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},
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page: "index.html",
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layout: "layout.html",
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expectedBody: "<body><div>Footer Content</div></body>",
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},
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{
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name: "simple page with Dict function and fragment",
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mockFS: fstest.MapFS{
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"index.html": {
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Data: []byte(`<button {{ template "fragments/button_attrs" (dict "ID" "myButton" "Class" "btn btn-primary") }}>Click Me</button>`),
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},
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"fragments/button_attrs.html": {
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Data: []byte(`id="{{.ID}}" class="{{.Class}}"`),
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},
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},
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page: "index.html",
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expectedBody: `<button id="myButton" class="btn btn-primary">Click Me</button>`,
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},
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{
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name: "error page not found due to wrong extension",
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mockFS: fstest.MapFS{
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"index.another": {
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Data: []byte(`<h1>Hello, wrong extension!</h1>`),
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},
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},
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page: "index.another",
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expectedError: true,
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expectedBody: "",
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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r := NewHTMLRender(tt.mockFS, false)
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for name, fn := range tt.customFuncs {
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r.AddFunc(name, fn)
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}
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rec := httptest.NewRecorder()
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var layouts []string
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if tt.layout != "" {
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layouts = append(layouts, tt.layout)
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}
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err := r.Render(rec, tt.page, tt.data, layouts...)
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if tt.expectedError {
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if err == nil {
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t.Error("expected error, got nil")
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}
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} else {
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if err != nil {
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t.Errorf("unexpected error: %v", err)
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}
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if got := strings.TrimSpace(rec.Body.String()); got != tt.expectedBody {
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t.Errorf("expected body %q, got %q", tt.expectedBody, got)
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}
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}
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})
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}
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}
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func Test_Dict(t *testing.T) {
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tests := []struct {
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name string
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given []any
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expected map[string]any
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}{
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{
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name: "valid - all strings",
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given: []any{"key", "value"},
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expected: map[string]any{
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"key": "value",
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},
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},
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{
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name: "valid - key string value int",
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given: []any{"age", 15},
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expected: map[string]any{
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"age": 15,
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},
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},
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{
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name: "error invalid dict call",
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given: []any{"error"},
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expected: map[string]any{
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"error": "invalid dict call",
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},
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},
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{
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name: "error dict keys must be strings",
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given: []any{1, "error"},
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expected: map[string]any{
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"error": "dict keys must be strings",
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},
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got := Dict(tt.given...)
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if !reflect.DeepEqual(got, tt.expected) {
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t.Errorf("expected %v, got %v", tt.expected, got)
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}
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})
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}
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}
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func Test_Cache(t *testing.T) {
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mockFS := fstest.MapFS{
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"index.html": {
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Data: []byte(`<h1>Hello Cached World</h1>`),
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},
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"main-layout.html": {
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Data: []byte(`<main>{{ embed }}</main>`),
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},
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}
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var buf bytes.Buffer
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originalLogger := slog.Default()
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slog.SetDefault(slog.New(slog.NewTextHandler(&buf, &slog.HandlerOptions{Level: slog.LevelDebug})))
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defer slog.SetDefault(originalLogger)
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r := NewHTMLRender(mockFS, true)
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rec1 := httptest.NewRecorder()
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err1 := r.Render(rec1, "index.html", nil, "main-layout.html")
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if err1 != nil {
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t.Errorf("unexpected error: %v", err1)
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}
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expected := "<main><h1>Hello Cached World</h1></main>"
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if got := strings.TrimSpace(rec1.Body.String()); got != expected {
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t.Errorf("expected body %q, got %q", expected, got)
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}
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if !strings.Contains(buf.String(), "template compiled and cached") {
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t.Error("expected 'template compiled and cached' message on first render")
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}
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buf.Reset()
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rec2 := httptest.NewRecorder()
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err2 := r.Render(rec2, "index.html", nil, "main-layout.html")
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if err2 != nil {
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t.Errorf("unexpected error: %v", err2)
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}
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if got := strings.TrimSpace(rec2.Body.String()); got != expected {
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t.Errorf("expected body %q, got %q", expected, got)
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}
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if strings.Contains(buf.String(), "template compiled and cached") {
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t.Error("did not expect 'template compiled and cached' message on second render")
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}
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}
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Reference in New Issue
Block a user