1 files changed, 52 insertions, 0 deletions
diff --git a/dom/base/test/meta_viewport/test_meta_viewport_change_content_among_multiple.html b/dom/base/test/meta_viewport/test_meta_viewport_change_content_among_multiple.html
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index 0000000000..8ec88b8920
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+++ b/dom/base/test/meta_viewport/test_meta_viewport_change_content_among_multiple.html
@@ -0,0 +1,52 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>content attribute changes among multiple meta viewport tags</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <meta id="first" name="viewport" content="width=980">
+  <meta id="second" name="viewport" content="width=device-width, initial-scale=1">
+  <script src="viewport_helpers.js"></script>
+</head>
+<body>
+  <script type="application/javascript">
+    "use strict";
+
+    add_task(async function change_content_attribute() {
+      await SpecialPowers.pushPrefEnv(scaleRatio(1.0));
+
+      let info = getViewportInfo(800, 480);
+      // The second meta tag is the one we use.
+      is(info.defaultZoom, 1, "initial zoom is 1");
+      is(info.width, 800, "width should be 800");
+      is(info.height, 480, "height should be 480");
+
+      // Change the content of the first one.
+      // eslint-disable-next-line no-undef
+      first.setAttribute("content", "width=640");
+
+      // Now the first one is prior to the second one.
+      info = getViewportInfo(800, 480);
+      fuzzeq(info.defaultZoom, 800/640, "initial scale is calculated based on width");
+      is(info.minZoom, 0.25, "minimum scale defaults to the absolute minimum");
+      is(info.maxZoom, 10, "maximum scale defaults to the absolute maximum");
+      is(info.width, 640, "width is the default width");
+      is(info.height, 480*640/800, "height is proportional to displayHeight");
+
+      // Cleat the second content.
+      // eslint-disable-next-line no-undef
+      second.setAttribute("content", "");
+
+      // The second one is prior to the first one, but the content is empty so
+      // that we should behave as if there is no meta viewport tag.
+      info = getViewportInfo(800, 480);
+      is(info.defaultZoom, 0.25, "initial scale is clamped to the default mimumim scale");
+      is(info.minZoom, 0.25, "minimum scale defaults to the absolute minimum");
+      is(info.maxZoom, 10, "maximum scale defaults to the absolute maximum");
+      is(info.width, 980, "width should be 980");
+      is(info.height,588, "height is proportional to displayHeight");
+    });
+  </script>
+</body>
+</html>