Tests that the README examples load, render and print what they claim

readme_test.go

@@ -0,0 +1,61 @@
+package fejkdata
+
+import (
+	"os"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+var jsonBlock = regexp.MustCompile("(?s)```json\n(.*?)```")
+
+func readme(t *testing.T) string {
+	t.Helper()
+	src, err := os.ReadFile("README.md")
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(src)
+}
+
+func TestReadmeExamplesLoadAndRender(t *testing.T) {
+	n := 0
+	for _, m := range jsonBlock.FindAllStringSubmatch(readme(t), -1) {
+		body := m[1]
+		if strings.Contains(body, "…") {
+			continue
+		}
+		f, err := New(WithDataPath(writeData(t, map[string]string{"example": body})), WithSeed(1))
+		if err != nil {
+			t.Errorf("README example does not load: %v\n%s", err, body)
+			continue
+		}
+		for i := 0; i < 20; i++ {
+			if _, err := f.Fake("example"); err != nil {
+				t.Errorf("README example does not render: %v\n%s", err, body)
+				break
+			}
+		}
+		n++
+	}
+	if n < 8 {
+		t.Fatalf("found only %d README examples", n)
+	}
+}
+
+func TestReadmeSQLExampleOutput(t *testing.T) {
+	src := readme(t)
+	src = src[strings.Index(src, "### Your own data"):]
+	block := jsonBlock.FindStringSubmatch(src)
+	want := regexp.MustCompile(`(?m)^# (INSERT .*)$`).FindStringSubmatch(src)
+	if block == nil || want == nil {
+		t.Fatal("README lost the SQL example or its printed output")
+	}
+	f, err := New(WithDataPath(writeData(t, map[string]string{"sql": block[1]})), WithSeed(1))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := fake(t, f, "sql"); got != want[1] {
+		t.Errorf("README SQL example with seed 1 = %q, README prints %q", got, want[1])
+	}
+}