type tests (#1337)

* tests salvaged from observablehq/plot#1024

* fix crash in valueof when the data is not iterable

* avoid the nullish test in map

* move null test back to map

* consolidate tests

* remove "valid input data" type tests

* test array value

---------

Co-authored-by: Mike Bostock <[email protected]>

Author: Fil

src/options.js

@@ -14,7 +14,7 @@ export function valueof(data, value, type) {
     ? maybeTypedMap(data, value, type)
     : valueType === "number" || value instanceof Date || valueType === "boolean"
     ? map(data, constant(value), type)
-    : value && typeof value.transform === "function"
+    : typeof value?.transform === "function"
     ? maybeTypedArrayify(value.transform(data), type)
     : maybeTypedArrayify(value, type);
 }
@@ -128,7 +128,7 @@ export function arrayify(data) {
 // An optimization of type.from(values, f): if the given values are already an
 // instanceof the desired array type, the faster values.map method is used.
 export function map(values, f, type = Array) {
-  return values instanceof type ? values.map(f) : type.from(values, f);
+  return values == null ? values : values instanceof type ? values.map(f) : type.from(values, f);
 }
 
 // An optimization of type.from(values): if the given values are already an

test/options-d-test.ts

@@ -0,0 +1,21 @@
+import {valueof} from "../src/options.js";
+
+// A function is not a valid input data
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-expect-error
+valueof(() => {}, "field");
+
+// A Promise is not a valid input data
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-expect-error
+valueof(new Promise(() => {}), "field");
+
+// A symbol is not a valid value
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-expect-error
+valueof(null, Symbol("field"));
+
+// A bigint is not a valid value
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-expect-error
+valueof(null, 2n);

test/options-test.js

@@ -114,3 +114,28 @@ it("valueof returns arrays that match the specified type as-is", () => {
   assert.strictEqual(valueof(m, identity, Float32Array), m);
   assert.strictEqual(valueof(m, identity, My32Array), m);
 });
+
+it("valueof returns the given array value", () => {
+  const a = [1, 2, 3];
+  assert.strictEqual(valueof(null, a), a);
+  assert.strictEqual(valueof(undefined, a), a);
+  assert.strictEqual(valueof([], a), a);
+});
+
+it("valueof accepts complicated data with the proper accessor", () => {
+  const m = [(d) => d, new Promise(() => {})];
+  assert.deepStrictEqual(valueof(m, String), ["(d) => d", "[object Promise]"]);
+});
+
+it("data passed to valueof can be nullish and generated by the transform method", () => {
+  assert.deepStrictEqual(valueof(undefined, {transform: () => [1, "text"]}), [1, "text"]);
+  assert.deepStrictEqual(valueof(null, {transform: () => [1, "text"]}, Float32Array), Float32Array.of(1, NaN));
+  assert.deepStrictEqual(valueof(null, {transform: () => new Float64Array(2)}, Array), [0, 0]);
+});
+
+it("valueof does not crash on nullish data with an accessor", () => {
+  const a = () => 1;
+  assert.strictEqual(valueof(null, a), null);
+  assert.strictEqual(valueof(undefined, a), undefined);
+  assert.deepStrictEqual(valueof(0, a), []); // ill-defined, but not crashing
+});