diff --git a/packages/ejson/package.js b/packages/ejson/package.js
index 26a33d4b35..7b4f238aa6 100644
--- a/packages/ejson/package.js
+++ b/packages/ejson/package.js
@@ -6,7 +6,7 @@ Package.describe({
 Package.on_use(function (api) {
   api.use(['json', 'underscore']);
   api.exportSymbol('EJSON');
-  api.exportSymbol('_EJSONTest');
+  api.exportSymbol('_EJSONTest', {testOnly: true});
   api.add_files('ejson.js', ['client', 'server']);
   api.add_files('base64.js', ['client', 'server']);
 });
diff --git a/packages/email/package.js b/packages/email/package.js
index 393fc107ff..27d22beb5f 100644
--- a/packages/email/package.js
+++ b/packages/email/package.js
@@ -9,7 +9,7 @@ Npm.depends({mailcomposer: "0.1.15", simplesmtp: "0.1.25", "stream-buffers": "0.
 Package.on_use(function (api) {
   api.use('underscore', 'server');
   api.exportSymbol('Email', 'server');
-  api.exportSymbol('_EmailTest', 'server');
+  api.exportSymbol('_EmailTest', 'server', {testOnly: true});
   api.add_files('email.js', 'server');
 });
 
diff --git a/packages/livedata/package.js b/packages/livedata/package.js
index a7cb9def76..3a9eb2bf38 100644
--- a/packages/livedata/package.js
+++ b/packages/livedata/package.js
@@ -26,7 +26,7 @@ Package.on_use(function (api) {
   api.exportSymbol('DDP');
   api.exportSymbol('DDPServer', 'server');
 
-  api.exportSymbol('_LivedataTest');
+  api.exportSymbol('_LivedataTest', {testOnly: true});
 
   // Transport
   api.use('reload', 'client');
diff --git a/packages/mongo-livedata/package.js b/packages/mongo-livedata/package.js
index d674e56643..e3704754be 100644
--- a/packages/mongo-livedata/package.js
+++ b/packages/mongo-livedata/package.js
@@ -26,7 +26,7 @@ Package.on_use(function (api) {
   // Allow us to detect 'autopublish', and publish collections if it's loaded.
   api.use('autopublish', 'server', {weak: true});
 
-  api.exportSymbol('_MongoLivedataTest', 'server');
+  api.exportSymbol('_MongoLivedataTest', 'server', {testOnly: true});
 
   api.add_files('mongo_driver.js', 'server');
   api.add_files('local_collection_driver.js', ['client', 'server']);
diff --git a/packages/oauth/package.js b/packages/oauth/package.js
index ad92dc44a0..5c292869e5 100644
--- a/packages/oauth/package.js
+++ b/packages/oauth/package.js
@@ -9,7 +9,7 @@ Package.on_use(function (api) {
   api.use(['underscore', 'service-configuration'], 'server');
 
   api.exportSymbol('Oauth');
-  api.exportSymbol('_OauthTest', 'server');
+  api.exportSymbol('_OauthTest', 'server', {testOnly: true});
 
   api.add_files('oauth_client.js', 'client');
   api.add_files('oauth_server.js', 'server');
diff --git a/packages/oauth1/package.js b/packages/oauth1/package.js
index ce76adfaa8..0dd304b6b9 100644
--- a/packages/oauth1/package.js
+++ b/packages/oauth1/package.js
@@ -11,7 +11,7 @@ Package.on_use(function (api) {
   api.use('http', 'server');
 
   api.exportSymbol('OAuth1Binding', 'server');
-  api.exportSymbol('_OAuth1Test', 'server');
+  api.exportSymbol('_OAuth1Test', 'server', {testOnly: true});
 
   api.add_files('oauth1_binding.js', 'server');
   api.add_files('oauth1_server.js', 'server');
diff --git a/packages/routepolicy/package.js b/packages/routepolicy/package.js
index 8b3db515bc..da08d2699c 100644
--- a/packages/routepolicy/package.js
+++ b/packages/routepolicy/package.js
@@ -9,7 +9,7 @@ Package.on_use(function (api) {
   // Package.webapp and only after initial load.
   api.use('webapp', 'server', {unordered: true});
   api.exportSymbol('RoutePolicy', 'server');
-  api.exportSymbol('_RoutePolicyTest', 'server');
+  api.exportSymbol('_RoutePolicyTest', 'server', {testOnly: true});
   api.add_files('routepolicy.js', 'server');
 });
 
diff --git a/packages/spark/package.js b/packages/spark/package.js
index 77bb36b188..932bc455d7 100644
--- a/packages/spark/package.js
+++ b/packages/spark/package.js
@@ -9,7 +9,7 @@ Package.on_use(function (api) {
           'client');
 
   api.exportSymbol('Spark', 'client');
-  api.exportSymbol('_SparkTest', 'client');
+  api.exportSymbol('_SparkTest', 'client', {testOnly: true});
 
   api.add_files(['spark.js', 'patch.js', 'convenience.js',
                  'utils.js'], 'client');
diff --git a/tools/linker.js b/tools/linker.js
index 1b1d24fffe..73dfb32302 100644
--- a/tools/linker.js
+++ b/tools/linker.js
@@ -462,8 +462,8 @@ var bannerPadding = function (bannerWidth) {
 //  - sourcePath: path to use in error messages
 //  - sourceMap: an optional source map (as string) for the input file
 //
-// declaredExports: an array of symbols that the module exports.  null
-// if our slice isn't allowed to have exports.
+// declaredExports: an array of symbols that the module exports.  null if our
+// slice isn't allowed to have exports. Symbols are {name,testOnly} pairs.
 //
 // useGlobalNamespace: make the top level namespace be the same as the
 // global namespace, so that symbols are accessible from the
diff --git a/tools/packages.js b/tools/packages.js
index beb5739d09..e3fbd1802c 100644
--- a/tools/packages.js
+++ b/tools/packages.js
@@ -399,7 +399,7 @@ _.extend(Slice.prototype, {
         rootOutputPath: self.pkg.serveRoot,
         arch: self.arch,
         fileOptions: fileOptions,
-        declaredExports: self.declaredExports,
+        declaredExports: _.pluck(self.declaredExports, 'name'),
         read: function (n) {
           if (n === undefined || readOffset + n > contents.length)
             n = contents.length - readOffset;
@@ -493,7 +493,7 @@ _.extend(Slice.prototype, {
         "/packages/" + self.pkg.name +
         (self.sliceName === "main" ? "" : ("." + self.sliceName)) + ".js",
       name: self.pkg.name || null,
-      declaredExports: self.declaredExports,
+      declaredExports: _.pluck(self.declaredExports, 'name'),
       jsAnalyze: jsAnalyze
     });
 
@@ -517,14 +517,14 @@ _.extend(Slice.prototype, {
 
     self.packageVariables = [];
     var packageVariableNames = {};
-    _.each(self.declaredExports, function (name) {
-      if (_.has(packageVariableNames, name))
+    _.each(self.declaredExports, function (symbol) {
+      if (_.has(packageVariableNames, symbol.name))
         return;
       self.packageVariables.push({
-        name: name,
-        export: true
+        name: symbol.name,
+        export: symbol.testOnly? "tests" : true
       });
-      packageVariableNames[name] = true;
+      packageVariableNames[symbol.name] = true;
     });
     _.each(results.assignedVariables, function (name) {
       if (_.has(packageVariableNames, name))
@@ -580,8 +580,9 @@ _.extend(Slice.prototype, {
         if (! otherSlice.isBuilt)
           throw new Error("dependency wasn't built?");
         _.each(otherSlice.packageVariables, function (symbol) {
-          // XXX implement test-only exports
-          if (symbol.export)
+          // Slightly hacky implementation of test-only exports.
+          if (symbol.export === true ||
+              (symbol.export === "tests" && self.sliceName === "tests"))
             imports[symbol.name] = otherSlice.pkg.name;
         });
       });
@@ -1586,13 +1587,22 @@ _.extend(Package.prototype, {
           //
           // @param symbols String (eg "Foo") or array of String
           // @param where 'client', 'server', or an array of those
-          exportSymbol: function (symbols, where) {
+          // @param options 'testOnly', boolean.
+          exportSymbol: function (symbols, where, options) {
             if (role === "test") {
               buildmessage.error("You cannot export symbols from a test.",
                                  { useMyCaller: true });
               // recover by ignoring
               return;
             }
+            // Support `api.exportSymbol("FooTest", {testOnly: true})` without
+            // where.
+            if (_.isObject(where) && !_.isArray(where) && !options) {
+              options = where;
+              where = null;
+            }
+            options = options || {};
+
             symbols = toArray(symbols);
             where = toWhereArray(where);
 
@@ -1605,7 +1615,7 @@ _.extend(Package.prototype, {
                 return;
               }
               _.each(where, function (w) {
-                exports[w].push(symbol);
+                exports[w].push({name: symbol, testOnly: !!options.testOnly});
               });
             });
           },