squash: add headers() to the HTTPEmitter function

Fixes: #149

Signed-off-by: Lance Ball <[email protected]>

Author: lance

lib/bindings/http/http_emitter.js

@@ -61,6 +61,26 @@ class HTTPEmitter {
     }
     throw new TypeError(`Unknown transport mode ${mode}.`);
   }
+
+  /**
+   * Returns the HTTP headers that will be sent for this event when the HTTP transmission
+   * mode is "binary". Events sent over HTTP in structured mode only have a single CE header
+   * and that is "ce-id", corresponding to the event ID.
+   * @param {CloudEvent} event a CloudEvent
+   * @returns {Object} the headers that will be sent for the event
+   */
+  headers(event) {
+    const headers = {};
+
+    Object.keys(this.binary.headerByGetter)
+      .filter((getter) => event[getter]())
+      .forEach((getter) => {
+        const header = this.binary.headerByGetter[getter];
+        headers[header.name] = header.parser(event[getter]());
+      });
+
+    return headers;
+  }
 }
 
 module.exports = HTTPEmitter;

test/bindings/http/http_emitter_test.js

@@ -65,6 +65,15 @@ describe("HTTP Transport Binding Emitter for CloudEvents", () => {
         }).catch(expect.fail);
     });
 
+    it("Provides the HTTP headers for a binary event", () => {
+      const headers = emitter.headers(event);
+      expect(headers[BINARY_HEADERS_1.TYPE]).to.equal(event.getType());
+      expect(headers[BINARY_HEADERS_1.SPEC_VERSION]).to.equal(event.getSpecversion());
+      expect(headers[BINARY_HEADERS_1.SOURCE]).to.equal(event.getSource());
+      expect(headers[BINARY_HEADERS_1.ID]).to.equal(event.getId());
+      expect(headers[BINARY_HEADERS_1.TIME]).to.equal(event.getTime());
+    });
+
     it("Sends a structured 1.0 CloudEvent if specified", () => {
       emitter.send(event, { mode: "structured" })
         .then((response) => {
@@ -128,6 +137,15 @@ describe("HTTP Transport Binding Emitter for CloudEvents", () => {
         }).catch(expect.fail);
     });
 
+    it("Provides the HTTP headers for a binary event", () => {
+      const headers = emitter.headers(event);
+      expect(headers[BINARY_HEADERS_03.TYPE]).to.equal(event.getType());
+      expect(headers[BINARY_HEADERS_03.SPEC_VERSION]).to.equal(event.getSpecversion());
+      expect(headers[BINARY_HEADERS_03.SOURCE]).to.equal(event.getSource());
+      expect(headers[BINARY_HEADERS_03.ID]).to.equal(event.getId());
+      expect(headers[BINARY_HEADERS_03.TIME]).to.equal(event.getTime());
+    });
+
     it("Sends a structured 0.3 CloudEvent if specified", () => {
       emitter.send(event, { mode: "structured", foo: "bar" })
         .then((response) => {