fix(core): prefer sample/default over empty primitive array

Author: kylef

packages/api-elements/CHANGELOG.md

@@ -1,5 +1,12 @@
 # API Elements (JavaScript) CHANGELOG
 
+## Master
+
+### Bug Fixes
+
+- Generating a value from an element will now prefer sample/default values for
+  arrays which contain empty primitive values.
+
 ## 0.2.6 (2020-07-01)
 
 ### Bug Fixes

packages/api-elements/lib/define-value-of.js

@@ -85,7 +85,16 @@ function findFirstSample(e) {
 
 const isPrimitive = e => (e instanceof StringElement) || (e instanceof NumberElement) || (e instanceof BooleanElement);
 const isEnumElement = e => e instanceof EnumElement;
-const isPlural = e => e instanceof ArrayElement;
+const isArrayElement = e => e instanceof ArrayElement;
+
+const hasSample = e => findFirstSample(e) !== null;
+const hasDefault = e => findDefault(e) !== null;
+const hasContent = e => e.content !== undefined;
+const hasValue = R.anyPass([hasContent, hasSample, hasDefault]);
+const hasNoValue = R.complement(hasValue);
+const isNoValuePrimitive = R.both(isPrimitive, hasNoValue);
+const isNonEmptyArrayElement = e => isArrayElement(e) && e.content && !e.isEmpty;
+
 
 function trivialValue(e) {
   if (e instanceof BooleanElement) {
@@ -113,8 +122,10 @@ function mapValue(e, options, f, elements) {
   }
 
   const opts = updateTypeAttributes(e, options);
-  if (e.content && (!isPlural(e) || !e.isEmpty)) {
+
+  if (e.content && !(isArrayElement(e) && e.content.every(isNoValuePrimitive))) {
     const result = f(e, opts, elements, 'content');
+
     if (undefined !== result) {
       return result;
     }
@@ -136,6 +147,15 @@ function mapValue(e, options, f, elements) {
     }
   }
 
+  // reconsider content for array element (prefer sample/default first)
+  if (isNonEmptyArrayElement(e)) {
+    const result = f(e, opts, elements, 'content');
+
+    if (undefined !== result) {
+      return result;
+    }
+  }
+
   if (isFlag(NULLABLE_FLAG, opts)) {
     const result = f(new NullElement(), opts, elements, 'nullable');
     if (undefined !== result) {
@@ -180,7 +200,7 @@ function mapValue(e, options, f, elements) {
     }
   }
 
-  if (isPlural(e) && e.isEmpty) {
+  if (isArrayElement(e) && e.isEmpty) {
     return f(e, opts, elements, 'generated');
   }
 

packages/api-elements/test/value-of-test.js

@@ -700,6 +700,25 @@ describe('valueOf ArrayElement', () => {
     expect(value).to.deep.equal([4, 2]);
   });
 
+  it('prefers samples over empty primitive value', () => {
+    const element = new ArrayElement([new NumberElement()]);
+    element.attributes.set('default', new ArrayElement([4, 2]));
+    element.attributes.set('samples', new ArrayElement([
+      new ArrayElement([2, 'hello']),
+    ]));
+    const value = element.valueOf();
+
+    expect(value).to.deep.equal([2, 'hello']);
+  });
+
+  it('prefers default over empty primitive value', () => {
+    const element = new ArrayElement([new NumberElement()]);
+    element.attributes.set('default', new ArrayElement([4, 2]));
+    const value = element.valueOf();
+
+    expect(value).to.deep.equal([4, 2]);
+  });
+
   it('generates [] if no content, default, samples and not nullable', () => {
     const element = new ArrayElement();
     const value = element.valueOf();