datatype_test.go

@@ -0,0 +1,161 @@
+package fejkdata
+
+import (
+	"encoding/json"
+	"regexp"
+	"slices"
+	"strings"
+	"testing"
+)
+
+func TestDatatypeAndNullSitOnlyInAColumn(t *testing.T) {
+	for _, src := range []string{
+		`{"format":"","age":{"format":"{int(18,99)}","datatype":"integer"}}`,
+		`{"format":"","n":{"format":"42","datatype":"integer"}}`,
+		`{"format":"","gone":null}`,
+		`{"format":"","middle":[null,"Ann","Eva"]}`,
+		`{"format":"","age":[null,{"format":"{int(18,99)}","datatype":"integer","weight":9}]}`,
+		`{"format":"","pick":[[null,"a"],"b"]}`,
+	} {
+		if _, err := compile(parse(t, src)); err != nil {
+			t.Errorf("compile(%s) = %v, want a column to take a datatype and null", src, err)
+		}
+	}
+	for src, want := range map[string]string{
+		`{"format":"","n":{"format":"1","datatype":"int"}}`:                             `datatype takes "integer", "number" or "boolean", got "int"`,
+		`{"format":"","n":{"format":"1","datatype":1}}`:                                 "datatype must be a string",
+		`{"format":"{int(1,9)}","datatype":"integer"}`:                                  "datatype only types a record column",
+		`[{"format":"1","datatype":"integer"},"x"]`:                                     "datatype only types a record column",
+		`{"format":"{p}","p":{"format":"{n}","n":{"format":"1","datatype":"integer"}}}`: "datatype only types a record column",
+		`{"format":"{n}","repeat":2,"n":{"format":"1","datatype":"integer"}}`:           "datatype only types a record column",
+		`null`: `so write ""`,
+		`{"format":"{p}","p":{"format":"{x}","x":[null,"a"]}}`:        `so write ""`,
+		`{"format":"","c":[{"format":"1","datatype":"integer"},"x"]}`: "a column holds one datatype",
+	} {
+		if _, err := compile(parse(t, src)); err == nil || !strings.Contains(err.Error(), want) {
+			t.Errorf("compile(%s) = %v, want an error containing %q", src, err, want)
+		}
+	}
+}
+
+func TestDatatypeRejectsARenderItsTypeRejects(t *testing.T) {
+	cat := `[{"format":"{code}","code":"200"},{"format":"{code}","code":"2x"}]`
+	for _, c := range []struct{ name, column, want string }{
+		{"a leading zero", `{"format":"{digits(3)}","datatype":"integer"}`, "which is not an integer"},
+		{"a fraction", `{"format":"{v}","v":["1","1.5"],"datatype":"integer"}`, `can render "1.5", which is not an integer`},
+		{"a signed sample before digits", `{"format":"{int(-5,5)}{digits(2)}","datatype":"integer"}`, "which is not an integer"},
+		{"a separator", `{"format":"{int(1,9)}","repeat":2,"separator":",","datatype":"integer"}`, "which is not an integer"},
+		{"through a reference", `{"format":"{/cat.code}","datatype":"integer"}`, `can render "2x"`},
+		{"a bare dot", `{"format":".5","datatype":"number"}`, `can render ".5", which is not a number`},
+		{"a trailing dot", `{"format":"{int(1,9)}.","datatype":"number"}`, "which is not a number"},
+		{"a plus sign", `{"format":"+1","datatype":"number"}`, `can render "+1"`},
+		{"a capital", `{"format":"{b}","b":["true","True"],"datatype":"boolean"}`, `can render "True", which is not a boolean`},
+		{"an upper-casing transform", `{"format":"{uppercase(b)}","b":["true","false"],"datatype":"boolean"}`, "which is not a boolean"},
+		{"an operand that is not always a number", `{"format":"{calc(a * 2)}","a":["1","x"],"datatype":"number"}`, `operand "a" can render "x"`},
+		{"a divisor that can be zero", `{"format":"{calc(a / b)}","a":"{int(1,9)}","b":"{int(0,9)}","datatype":"number"}`, "divides by b, which can be zero"},
+		{"an overflow", `{"format":"{calc(a * a)}","a":"{digits(200)}","datatype":"number"}`, "can overflow"},
+		{"a division in an integer column", `{"format":"{calc(a / b)}","a":"{int(1,9)}","b":"{int(1,9)}","datatype":"integer"}`, "which is not an integer"},
+	} {
+		row := `{"format":"","col":` + c.column + `}`
+		_, err := New(WithoutShippedData(), WithDataPath(writeData(t, map[string]string{"cat": cat, "row": row})))
+		if err == nil || !strings.Contains(err.Error(), c.want) {
+			t.Errorf("%s: New = %v, want an error containing %q", c.name, err, c.want)
+		}
+		f := newGenerator(t, writeData(t, map[string]string{"cat": cat}))
+		if _, err := f.NewTemplate(row); err == nil || !strings.Contains(err.Error(), c.want) {
+			t.Errorf("%s: NewTemplate = %v, want the inline template refused the same way", c.name, err)
+		}
+	}
+}
+
+var integerText = regexp.MustCompile(`^-?(0|[1-9][0-9]*)$`)
+
+func TestDatatypeAcceptsAColumnThatAlwaysParses(t *testing.T) {
+	cat := `[{"format":"{code}","code":"200"},{"format":"{code}","code":"404"}]`
+	for _, column := range []string{
+		`{"format":"{int(1,99)}","datatype":"integer"}`,
+		`{"format":"-{int(1,9)}","datatype":"integer"}`,
+		`{"format":"1{digits(2)}","datatype":"integer"}`,
+		`{"format":"{seq()}","datatype":"integer"}`,
+		`{"format":"{/cat.code}","datatype":"integer"}`,
+		`{"format":"{float(-1,1,2)}","datatype":"number"}`,
+		`{"format":"{int(1,9)}e{int(1,9)}","datatype":"number"}`,
+		`{"format":"6.022e23","datatype":"number"}`,
+		`{"format":"{lowercase(b)}","b":["TRUE","False"],"datatype":"boolean"}`,
+		`{"format":"{calc(net * qty, 2)}","net":["19.99","5.00"],"qty":["3","7"],"datatype":"number"}`,
+		`{"format":"{calc(a + b)}","a":"{int(1,9)}","b":"{int(-9,9)}","datatype":"integer"}`,
+		`{"format":"{calc(a / (b + 1), 2)}","a":"{int(1,9)}","b":"{digits(2)}","datatype":"number"}`,
+		`{"format":"{calc(a / b, 0)}","a":"{int(1,9)}","b":"{int(1,9)}","datatype":"integer"}`,
+		`{"format":"{calc(sub * 1.25, 2)}","sub":{"format":"{calc(a * b)}","a":"{int(1,9)}","b":"{float(0,5,2)}"},"datatype":"number"}`,
+	} {
+		row := `{"format":"","col":` + column + `}`
+		f, err := New(WithoutShippedData(), WithDataPath(writeData(t, map[string]string{"cat": cat, "row": row})), WithSeed(1))
+		if err != nil {
+			t.Errorf("%s: New = %v, want it loaded", column, err)
+			continue
+		}
+		for i := 0; i < 200; i++ {
+			r, err := f.FakeRecord("row")
+			if err != nil {
+				t.Fatal(err)
+			}
+			var m map[string]any
+			if err := json.Unmarshal([]byte(r.JSON()), &m); err != nil {
+				t.Errorf("%s: JSON() = %s is not JSON: %v", column, r.JSON(), err)
+				break
+			}
+			c := r.Columns()[0]
+			_, isBool := m["col"].(bool)
+			_, isNumber := m["col"].(float64)
+			if c.DataType == DataTypeBoolean && !isBool || c.DataType != DataTypeBoolean && !isNumber || c.DataType == DataTypeInteger && !integerText.MatchString(c.Value) {
+				t.Errorf("%s: column %+v written as %s, want its datatype", column, c, r.JSON())
+				break
+			}
+		}
+	}
+}
+
+func TestNullColumn(t *testing.T) {
+	dir := writeData(t, map[string]string{
+		"row": `{"format":"[{middle}]","gone":null,"middle":[null,"Ann"],"score":[null,{"format":"{int(1,9)}","datatype":"integer"}]}`,
+	})
+	f := newGenerator(t, dir, WithSeed(1))
+	drew := map[bool]bool{}
+	for i := 0; i < 100; i++ {
+		r, err := f.FakeRecord("row")
+		if err != nil {
+			t.Fatal(err)
+		}
+		gone, middle, score := r.Columns()[0], r.Columns()[1], r.Columns()[2]
+		if !gone.Null || gone.Value != "" || gone.DataType != DataTypeString {
+			t.Fatalf("gone = %+v, want a null string column every draw", gone)
+		}
+		if middle.Null == (middle.Value == "Ann") {
+			t.Fatalf("middle = %+v, want null or Ann", middle)
+		}
+		if score.DataType != DataTypeInteger {
+			t.Fatalf("score = %+v, want the integer its non-null item declares, null or not", score)
+		}
+		drew[middle.Null] = true
+	}
+	if len(drew) != 2 {
+		t.Errorf("middle drew only null=%v in 100 records, want both", drew)
+	}
+	if v := fake(t, f, "row"); v != "[]" && v != "[Ann]" {
+		t.Errorf("Fake(row) = %q, want a null to render as \"\"", v)
+	}
+	if v := fake(t, f, "row.gone"); v != "" {
+		t.Errorf("Fake(row.gone) = %q, want \"\"", v)
+	}
+	if !slices.Contains(f.List(), "row.gone") {
+		t.Errorf("List() = %v, want the null column row.gone, which Fake accepts", f.List())
+	}
+}
+
+func TestEveryBuiltinSaysWhatItEmits(t *testing.T) {
+	for name, b := range builtins {
+		if _, isTransform := transforms[name]; b.emits == nil && name != "calc" && !isTransform {
+			t.Errorf("builtin %s declares no emits, so a typed column calling it cannot be checked", name)
+		}
+	}
+}

one_spelling_test.go

@@ -36,6 +36,7 @@ func TestInertObjectIsRejected(t *testing.T) {
 		`{"format":"{x}","x":"v","repeat":1}`:                  "repeat 1",
 		`{"format":"{x}","x":"v","separator":","}`:             "separator",
 		`{"format":"{x}","x":"v","repeat":2,"separator":""}`:   "default",
+		`{"format":"","n":{"format":"1","datatype":"string"}}`: `datatype "string" is the default`,
 	} {
 		if _, err := compile(parse(t, src)); err == nil || !strings.Contains(err.Error(), want) {
 			t.Errorf("compile(%s) = %v, want an error mentioning %s", src, err, want)

readme_test.go

@@ -1,6 +1,7 @@
 package fejkdata
 
 import (
+	"encoding/json"
 	"os"
 	"regexp"
 	"strings"
@@ -87,3 +88,43 @@ func TestReadmeSQLExampleOutput(t *testing.T) {
 		t.Errorf("README SQL example with seed 1 = %q, README prints %q", got, want[1])
 	}
 }
+
+func TestReadmeDatatypeExample(t *testing.T) {
+	src := readme(t)
+	i := strings.Index(src, "### Datatype")
+	if i < 0 {
+		t.Fatal("README lost the Datatype section")
+	}
+	block := jsonBlock.FindStringSubmatch(src[i:])
+	f, err := New(WithDataPath(writeData(t, map[string]string{"order": block[1]})), WithSeed(1))
+	if err != nil {
+		t.Fatal(err)
+	}
+	r, err := f.FakeRecord("order")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m map[string]any
+	if err := json.Unmarshal([]byte(r.JSON()), &m); err != nil {
+		t.Fatalf("JSON() = %s: %v", r.JSON(), err)
+	}
+	shown := map[DataType]bool{}
+	for _, c := range r.Columns() {
+		shown[c.DataType] = true
+		var ok bool
+		switch c.DataType {
+		case DataTypeBoolean:
+			_, ok = m[c.Name].(bool)
+		case DataTypeInteger, DataTypeNumber:
+			_, ok = m[c.Name].(float64)
+		default:
+			_, ok = m[c.Name].(string)
+		}
+		if !ok {
+			t.Errorf("column %q, datatype %s, written as %s", c.Name, c.DataType, r.JSON())
+		}
+	}
+	if !shown[DataTypeInteger] || !shown[DataTypeNumber] || !shown[DataTypeBoolean] {
+		t.Errorf("README Datatype example shows %v, want an integer, a number and a boolean column", shown)
+	}
+}

record_test.go

@@ -3,6 +3,7 @@ package fejkdata
 import (
 	"encoding/csv"
 	"encoding/json"
+	"reflect"
 	"strings"
 	"testing"
 )
@@ -133,8 +134,8 @@ func TestRecordCSV(t *testing.T) {
 }
 
 func TestRecordCSVEmptyValueStaysARow(t *testing.T) {
-	dir := writeData(t, map[string]string{"blank": `{"format": "", "note": ""}`})
-	f := newGenerator(t, dir, WithSeed(1))
+	for _, body := range []string{`{"format": "", "note": ""}`, `{"format": "", "note": null}`} {
+		f := newGenerator(t, writeData(t, map[string]string{"blank": body}), WithSeed(1))
 		r, err := f.FakeRecord("blank")
 		if err != nil {
 			t.Fatal(err)
@@ -144,7 +145,41 @@ func TestRecordCSVEmptyValueStaysARow(t *testing.T) {
 			t.Fatalf("csv: %v", err)
 		}
 		if len(rows) != 2 || len(rows[1]) != 1 || rows[1][0] != "" {
-		t.Fatalf("one empty column parsed to %v, want a header and one row of one empty field", rows)
+			t.Fatalf("%s: one empty column parsed to %v, want a header and one row of one empty field", body, rows)
+		}
+	}
+}
+
+func TestRecordWritesTypedAndNullColumns(t *testing.T) {
+	dir := writeData(t, map[string]string{
+		"row": `{"format":"","age":{"format":"42","datatype":"integer"},"gone":null,"name":"O'Brien","nick":"","paid":{"format":"true","datatype":"boolean"},"price":{"format":"19.99","datatype":"number"}}`,
+	})
+	r, err := newGenerator(t, dir, WithSeed(1)).FakeRecord("row")
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := []Column{
+		{Name: "age", DataType: DataTypeInteger, Value: "42"},
+		{Name: "gone", Null: true},
+		{Name: "name", Value: "O'Brien"},
+		{Name: "nick"},
+		{Name: "paid", DataType: DataTypeBoolean, Value: "true"},
+		{Name: "price", DataType: DataTypeNumber, Value: "19.99"},
+	}
+	if got := r.Columns(); !reflect.DeepEqual(got, want) {
+		t.Errorf("Columns() = %+v, want %+v", got, want)
+	}
+	if got, want := r.JSON(), `{"age":42,"gone":null,"name":"O'Brien","nick":"","paid":true,"price":19.99}`; got != want {
+		t.Errorf("JSON() = %s, want %s", got, want)
+	}
+	if got, want := r.SQLInsert("t"), `INSERT INTO "t" ("age", "gone", "name", "nick", "paid", "price") VALUES (42, NULL, 'O''Brien', '', true, 19.99);`; got != want {
+		t.Errorf("SQLInsert() = %s, want %s", got, want)
+	}
+	if got, want := r.CSVLine(), `42,,O'Brien,"",true,19.99`; got != want {
+		t.Errorf("CSVLine() = %s, want %s: null an unquoted empty field, an empty string quoted", got, want)
+	}
+	if got := DataTypeNumber.String(); got != "number" {
+		t.Errorf("DataTypeNumber.String() = %q, want the data's spelling", got)
 	}
 }