throw errors when dash receives invalid args

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Fix links to pages within the document
 - Add support for named destinations
+- Throw errors when `dash(...)` is passed invalid lengths
 
 ### [v0.9.1] - 2019-04-30
 

docs/vector.md

@@ -145,7 +145,8 @@ The output of this example looks like this.
 
 The `dash` method allows you to create non-continuous dashed lines. It takes a
 length specifying how long each dash should be, as well as an optional hash
-describing the additional properties `space` and `phase`.
+describing the additional properties `space` and `phase`. Lengths must be positive
+numbers; `dash` will throw if passed invalid lengths.
 
 The `space` option defines the length of the space between each dash, and the `phase` option
 defines the starting point of the sequence of dashes. By default the `space`

lib/mixins/vector.js

@@ -63,20 +63,18 @@ export default {
 
   dash(length, options = {}) {
     let phase;
-    if (length == null) {
-      return this;
+    const originalLength = length;
+    if (!Array.isArray(length)) {
+      length = [length, options.space || length];
     }
-    if (Array.isArray(length)) {
-      length = length.map(v => number(v)).join(' ');
-      phase = options.phase || 0;
-      return this.addContent(`[${length}] ${number(phase)} d`);
-    } else {
-      const space = options.space != null ? options.space : length;
-      phase = options.phase || 0;
-      return this.addContent(
-        `[${number(length)} ${number(space)}] ${number(phase)} d`
-      );
+
+    const valid = length.every(x => Number.isFinite(x) && x > 0);
+    if(!valid) {
+      throw new Error(`dash(${JSON.stringify(originalLength)}, ${JSON.stringify(options)}) invalid, lengths must be numeric and greater than zero`);
     }
+    length = length.map(v => number(v)).join(' ');
+    phase = options.phase || 0;
+    return this.addContent(`[${length}] ${number(phase)} d`);
   },
 
   undash() {

tests/unit/document.spec.js

@@ -32,4 +32,5 @@ describe('PDFDocument', () => {
       expect(fontSpy).not.toBeCalled();
     });
   });
+
 });

tests/unit/vector.spec.js

@@ -111,5 +111,50 @@ describe('Vector Graphics', () => {
         `endobj`
       ]);
     });
+
+    describe('validation', () => {
+
+      test('length 1', () => {
+        const doc = new PDFDocument();
+
+        expect(() => doc.dash(1)).not.toThrow();
+      });
+
+      test('length 1.5', () => {
+        const doc = new PDFDocument();
+
+        expect(() => doc.dash(1.5)).not.toThrow();
+      });
+
+      test('length 0 throws', () => {
+        const doc = new PDFDocument();
+
+        expect(() => doc.dash(0)).toThrow('dash(0, {}) invalid, lengths must be numeric and greater than zero');
+      });
+
+      test('length -1 throws', () => {
+        const doc = new PDFDocument();
+
+        expect(() => doc.dash(-1)).toThrow('dash(-1, {}) invalid, lengths must be numeric and greater than zero');
+      });
+
+      test('length null throws', () => {
+        const doc = new PDFDocument();
+
+        expect(() => doc.dash(null)).toThrow('dash(null, {}) invalid, lengths must be numeric and greater than zero');
+      });
+
+      test('length array', () => {
+        const doc = new PDFDocument();
+
+        expect(() => doc.dash([2,3])).not.toThrow();
+      });
+
+      test('length array containing zeros throws', () => {
+        const doc = new PDFDocument();
+
+        expect(() => doc.dash([2, 0, 3])).toThrow('dash([2,0,3], {}) invalid, lengths must be numeric and greater than zero');
+      });
+    });
   });
 });