Don't copy package.json to build directory

We do not need to handle two relative paths because both the packaged
lib and test suite run through the /build directory, which means we
can support a single path.

The opencensus-exporter-ocagent has been updated to support the newly
exported version.

packages/opencensus-core/package.json

@@ -9,7 +9,7 @@
     "test": "nyc -x '**/test/**' --reporter=html --reporter=text mocha 'build/test/**/*.js'",
     "clean": "rimraf build/*",
     "check": "gts check",
-    "compile": "tsc -p . && cp package.json build/",
+    "compile": "tsc -p .",
     "fix": "gts fix",
     "prepare": "npm run compile",
     "pretest": "npm run compile",

packages/opencensus-core/src/common/version.ts

@@ -15,5 +15,14 @@
  * limitations under the License.
  */
 
-const pjson = require('../../package.json');
+type Package = {
+  version: string;
+};
+
+// Load the package details. Note that the `require` is performed at runtime,
+// which means the source files will be in the `/build` directory, so the
+// package path is relative to that location.
+const pjson: Package = require('../../../package.json');
+
+// Export the core package version
 export const version: string = pjson.version;

packages/opencensus-exporter-ocagent/src/ocagent.ts

@@ -15,7 +15,7 @@
  */
 
 import * as protoLoader from '@grpc/proto-loader';
-import {Exporter, ExporterBuffer, ExporterConfig, logger, Logger, RootSpan, SamplerBuilder} from '@opencensus/core';
+import {Exporter, ExporterBuffer, ExporterConfig, logger, Logger, RootSpan, SamplerBuilder, version as coreVersion} from '@opencensus/core';
 import * as tracing from '@opencensus/nodejs';
 import * as grpc from 'grpc';
 import * as os from 'os';
@@ -91,8 +91,7 @@ export class OCAgentExporter implements Exporter {
      * Get node properties
      */
     this.exporterVersion = require('../../package.json').version;
-    this.coreVersion =
-        require('../../node_modules/@opencensus/core/package.json').version;
+    this.coreVersion = coreVersion;
     this.hostName = os.hostname();
     this.processStartTimeMillis = Date.now() - (process.uptime() * 1000);