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+# Feature Policy Guide
+## How to Test a New Feature with Feature Policy
+
+This directory contains a framework to test features with feature policy.
+
+When adding a new feature to feature policy, the following cases should be tested:
+* feature enabled by header policy [HTTP tests]
+    + test when feature is enabled by feature policy HTTP header;
+* feature disabled by header policy [HTTP tests]
+    + test when feature is disabled by feature policy HTTP header;
+* feature enabled on self origin by header policy [HTTP tests]
+    + test when feature is enabled only on self origin by feature policy HTTP
+    header.
+* feature allowed by container policy (iframe "allow" attribute);
+    + test when feature is enabled by iframe "allow" attribute on self and cross
+    origins.
+* feature allowed by container policy, redirect on load.
+    + test when feature is enabled by iframe "allow" attribute when the iframe
+    is being redirected to a new origin upon loading
+
+### How to Use the Test Framework
+Use `test_feature_availability()` defined in
+`/feature-policy/resources/featurepolicy.js`. Please refer to the comments
+in `/feature-policy/resources/featurepolicy.js` for how this function works.
+
+### How to Write Header Policy Tests
+HTTP tests are used to test features with header policy.
+
+* Define the header policy in `<feature-name>-<enabled | disabled | enabled-on-self-origin>-by-feature-policy.https.sub.html.headers`. Example:
+
+    Feature-Policy: feature-name *
+
+
+* In `<feature-name>-<enabled | disabled | enabled-on-self-origin>-by-feature-policy.https.sub.html`:
+* test if feature is enabled / disabled in the main frame;
+* test if feature is enabled / disabled in a same-origin iframe;
+* test if feature is enabled / disabled in a cross-origin iframe.
+
+Examples:
+`/feature-policy/payment-disabled-by-feature-policy.https.sub.html`
+`/feature-policy/payment-disabled-by-feature-policy.https.sub.html.headers`
+
+### How to Write Container Policy Tests
+Simply use `test_feature_availability()` with the optional argument
+`feature_name` specified to test if:
+* feature is enabled / disabled in a same-origin iframe;
+* feature is enabled / disabled in a cross-origin iframe.
+
+Example:
+`/feature-policy/payment-allowed-by-feature-policy-attribute.https.sub.html`
+
+### How to Write Container Policy Tests with Redirect
+Similar to the section above, append
+`/feature-policy/resources/redirect-on-load.html#` to the argument `src`
+passed to `test_feature_availability()`.
+
+Example:
+`/feature-policy/payment-allowed-by-feature-policy-attribute-redirect-on-load.https.sub.html`
+