begin noodling on a little module of common idioms I use in personal projects

http/http.go

@@ -0,0 +1,42 @@
+package grabhttp
+
+import (
+	"encoding/json"
+	"io/fs"
+	"net/http"
+)
+
+type errorStruct struct {
+	Status string `json:"status"`
+	Error  string `json:"error"`
+}
+
+func StaticHandler(f fs.FS) http.Handler {
+	return http.FileServer(http.FS(f))
+}
+
+func WriteJSON(i interface{}, status int, w http.ResponseWriter, r *http.Request) {
+	b, err := json.Marshal(i)
+	if err != nil {
+		ErrorJSON(err, http.StatusInternalServerError, w, r)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	w.Write(b)
+	w.Write([]byte("\n"))
+}
+
+func WriteHTML(b []byte, status int, w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/html")
+	w.WriteHeader(status)
+	w.Write(b)
+	w.Write([]byte("\n"))
+}
+
+func ErrorJSON(err error, status int, w http.ResponseWriter, r *http.Request) {
+	WriteJSON(errorStruct{
+		Status: "error",
+		Error:  err.Error(),
+	}, status, w, r)
+}

http/http_test.go

@@ -0,0 +1,70 @@
+package grabhttp
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestWriteJSON(t *testing.T) {
+	testcases := []struct {
+		input   interface{}
+		code    int
+		outcode int
+		output  []byte
+	}{
+		{
+			input:  struct{}{},
+			code:   http.StatusOK,
+			output: []byte("{}\n"),
+		},
+		{
+			input:  struct{}{},
+			code:   http.StatusNotFound,
+			output: []byte("{}\n"),
+		},
+		{
+			input: struct {
+				Foo string
+			}{
+				Foo: "foo",
+			},
+			code:   http.StatusOK,
+			output: []byte(`{"Foo":"foo"}` + "\n"),
+		},
+		{
+			input: struct {
+				Foo struct {
+					Bar string `json:"quuz"`
+				}
+			}{
+				Foo: struct {
+					Bar string `json:"quuz"`
+				}{Bar: "foo"},
+			},
+			code:   http.StatusOK,
+			output: []byte(`{"Foo":{"quuz":"foo"}}` + "\n"),
+		},
+		{
+			input:   struct{ C func() }{C: func() {}},
+			code:    http.StatusOK,
+			outcode: http.StatusInternalServerError,
+			output:  []byte(`{"status":"error","error":"json: unsupported type: func()"}` + "\n"),
+		},
+	}
+	for i, c := range testcases {
+		w := httptest.NewRecorder()
+		WriteJSON(c.input, c.code, w, httptest.NewRequest("", "/", nil))
+		if w.Code != c.code && w.Code != c.outcode {
+			t.Logf("code mismatch on case %d", i)
+			t.Fail()
+		}
+		b, err := io.ReadAll(w.Body)
+		if err != nil || !bytes.Equal(b, c.output) {
+			t.Logf("failed: %s != %s", b, c.output)
+			t.Fail()
+		}
+	}
+}