multiple lookback tests

backend.js

@@ -97,6 +97,7 @@ Backend.prototype.getTile = function(z, x, y, callback) {
         } else if (typeof backend._lookback === 'number' &&
             err && err.message === 'Tile does not exist' &&
             lookbacks <= backend._lookback) {
+            lookbacks += 1
             bz = bz - 1;
             bx = Math.floor(x / Math.pow(2, z - bz));
             by = Math.floor(y / Math.pow(2, z - bz));

test/fixtures/l.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE Map[]>
+<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over" maximum-extent="-20037508.34,-20037508.34,20037508.34,20037508.34">
+
+<Parameters>
+  <Parameter name="bounds">-180,-85.0511,180,85.0511</Parameter>
+  <Parameter name="center">0,0,2</Parameter>
+  <Parameter name="format">png8:m=h</Parameter>
+  <Parameter name="minzoom">0</Parameter>
+  <Parameter name="maxzoom">8</Parameter>
+  <Parameter name="scale">1</Parameter>
+  <Parameter name="source">test:///l</Parameter>
+  <Parameter name="name"><![CDATA[test-l]]></Parameter>
+</Parameters>
+
+<Style name="_image" filter-mode="first">
+  <Rule>
+    <RasterSymbolizer opacity=".7" />
+  </Rule>
+</Style>
+
+<Layer name="_image"
+  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
+  <StyleName>_image</StyleName>
+</Layer>
+
+</Map>

test/test.js

@@ -17,6 +17,7 @@ var xml = {
     b: fs.readFileSync(path.resolve(__dirname + '/fixtures/b.xml'), 'utf8'),
     c: fs.readFileSync(path.resolve(__dirname + '/fixtures/c.xml'), 'utf8'),
     i: fs.readFileSync(path.resolve(__dirname + '/fixtures/i.xml'), 'utf8'),
+    l: fs.readFileSync(path.resolve(__dirname + '/fixtures/l.xml'), 'utf8'),
     space: fs.readFileSync(path.resolve(__dirname + '/fixtures/s p a c e/i.xml'), 'utf8'),
     expires: fs.readFileSync(path.resolve(__dirname + '/fixtures/expires.xml'), 'utf8'),
     invalid: fs.readFileSync(path.resolve(__dirname + '/fixtures/invalid.xml'), 'utf8')
@@ -116,6 +117,7 @@ var sources = {
     h: new Vector({ backend: new Testsource('b'), xml: xml.b, scale: 2 }),
     i: new Vector({ backend: new Testsource('i'), xml: xml.i }),
     'i@2x': new Vector({ backend: new Testsource('i'), xml: xml.i }),
+    l: new Vector({ backend: new Testsource('l'), xml: xml.l}),
     invalid: new Vector({ backend: new Testsource('invalid'), xml: xml.invalid })
 };
 var tests = {
@@ -141,7 +143,8 @@ var tests = {
     i: ['0.0.0', '1.0.0'],
     // Image sources.
     'i@2x': ['0.0.0', '1.0.0'],
-    l: ['0.0.0', '1.0.1', '2.1.1'],
+    // Image sources for multiple lookback
+    l: ['0.0.0', '1.0.0', '1.1.1', '2.0.0', '2.3.3'],
     // Invalid tiles that are empty
     invalid: ['1.1.0', '1.1.1'],
 

test/testsource.js

@@ -160,6 +160,7 @@ function Testsource(uri, callback) {
         minzoom: infos[uri].minzoom,
         maxzoom: infos[uri].maxzoom,
         fillzoom: infos[uri].fillzoom,
+        lookback: infos[uri].lookback,
         vector_layers: infos[uri].vector_layers
     };
     this.stats = {};