Fix a hang caused by bad interaction between new pool and testify

At present only the generated changefeed tests are affected, and
running gen_tests produces many distracting changes, so I manually
altered TearDownSuite() in only the changefeed tests.

(Ultimately I'd like to see #495 and #496 merged, after which
gen_tests can be run to fix TearDownSuite() in the other files
for consistency.)

This change also closes some cursors that were previously leaked in
hand-written tests.  In most cases this isn't necessary.  But like
the changefeed tests, sometimes the test framework uses multiple
goroutines, in which case the default single-connection pool will
block if any tests fail to close their cursors.

Finally, this includes a .travis.yml change previously submitted
in #494 so the build can be verified.

Author: Cody Jones

.travis.yml

@@ -7,11 +7,9 @@ go:
 
 go_import_path: gopkg.in/rethinkdb/rethinkdb-go.v6
 
-install: go get -t ./...
-
 before_script:
-  - source /etc/lsb-release && echo "deb http://download.rethinkdb.com/apt $DISTRIB_CODENAME main" | sudo tee /etc/apt/sources.list.d/rethinkdb.list
-  - wget -qO- http://download.rethinkdb.com/apt/pubkey.gpg | sudo apt-key add -
+  - source /etc/lsb-release && echo "deb https://download.rethinkdb.com/repository/ubuntu-$TRAVIS_DIST $TRAVIS_DIST main" | sudo tee /etc/apt/sources.list.d/rethinkdb.list
+  - wget -qO- https://download.rethinkdb.com/repository/raw/pubkey.gpg | sudo apt-key add -
   - sudo apt-get update
   - sudo apt-get install rethinkdb
   - rethinkdb > /dev/null 2>&1 &
@@ -20,6 +18,7 @@ before_script:
   - rethinkdb --port-offset 3 --directory rethinkdb_data3 --join localhost:29016 > /dev/null 2>&1 &
 
 script:
-  - go test -race .
-  - go test -tags='cluster' -short -race -v ./...
-  - GOMODULE111=off go test .
+  - GO111MODULE=on go test -race .
+  - GO111MODULE=on go test -tags='cluster' -short -race -v ./...
+  - GO111MODULE=on go test .
+

internal/integration/reql_tests/common.go

@@ -53,6 +53,8 @@ func runAndAssert(suite suite.Suite, expected, v interface{}, session *r.Session
 	}
 
 	assertExpected(suite, expected, cursor, err)
+
+	closeCursor(cursor)
 }
 
 func fetchAndAssert(suite suite.Suite, expected, result interface{}, count int) {
@@ -81,6 +83,20 @@ func fetchAndAssert(suite suite.Suite, expected, result interface{}, count int)
 	}
 
 	assertExpected(suite, expected, cursor, err)
+
+	closeCursor(cursor)
+}
+
+func closeCursor(c *r.Cursor) {
+	if c != nil {
+		/* Cursors should ordinarily be closed when they are no longer needed, otherwise an application using
+		   multiple goroutines might hang waiting for a free connection in the pool.  However, some of the
+		   generated changefeed tests expect the cursor will return additional changes after fetchAndAssert()
+		   is called.  This means we must leave test cursors hanging open for these tests to pass.
+		*/
+
+		//c.Close()
+	}
 }
 
 func maybeLen(v interface{}) interface{} {

internal/integration/reql_tests/reql_changefeeds_edge_test.go

@@ -50,15 +50,29 @@ func (suite *${module_name}Suite) SetupTest() {
 func (suite *${module_name}Suite) TearDownSuite() {
 	suite.T().Log("Tearing down ${module_name}Suite")
 
-	if suite.session != nil {
-		r.DB("rethinkdb").Table("_debug_scratch").Delete().Exec(suite.session)
-		%for var_name in table_var_names:
-		 r.DB("test").TableDrop("${var_name}").Exec(suite.session)
-		%endfor
-		r.DBDrop("test").Exec(suite.session)
+	/* This function will block if a cursor is left open by a test, because:
+	     * the pool only contains one connection by default,
+	     * that connection can only be used by the goroutine that acquired it (until it's released), and
+		 * stretchr/testify/suite runs SetupTest() and TestCases() in a different goroutine.
 
+	   It's easiest to circumvent this and use a new session rather than altering the core Rethink tests or the Go test generator.
+	*/
+	if suite.session != nil {
 		suite.session.Close()
 	}
+
+	session, err := r.Connect(r.ConnectOpts{
+		Address: url,
+	})
+	suite.Require().NoError(err, "Error returned when connecting to server")
+
+	r.DB("rethinkdb").Table("_debug_scratch").Delete().Exec(session)
+	%for var_name in table_var_names:
+		r.DB("test").TableDrop("${var_name}").Exec(session)
+	%endfor
+	r.DBDrop("test").Exec(session)
+
+	session.Close()
 }
 
 <%rendered_vars = set() %>\