Fix tests that failed when run concurrently

go test ./... would often fail because some tests in the main tern
package and the migrate package used the same database.

README.markdown

@@ -367,14 +367,17 @@ library can help.
 
 To run the tests tern requires two test databases to run migrations against.
 
-1. Create a new database for main tern program tests.
+1. Create a new database for main tern program tests (e.g. `tern_test`).
 2. Open testdata/tern.conf.example
 3. Enter the connection information.
-4. Save as testdata/tern.conf.
-5. Create another database for the migrate library tests.
-6. Run tests with the connection string for the migrate library tests in the MIGRATE_TEST_CONN_STRING environment variable
+4. Run tests with the connection string for the main tern program tests in the TERN_TEST_CONN_STRING environment variable.
+5. Save as testdata/tern.conf.
+6. Create another database for the migrate library tests (e.g. `tern_migrate_test`).
+7. Run tests with the connection string for the migrate library tests in the MIGRATE_TEST_CONN_STRING environment variable
 
-    MIGRATE_TEST_CONN_STRING="host=/private/tmp database=tern_migrate_test" go test ./...
+```
+TERN_TEST_CONN_STRING="host=/private/tmp database=tern_test" MIGRATE_TEST_CONN_STRING="host=/private/tmp database=tern_migrate_test" go test ./...
+```
 
 ## Prior Ruby Gem Version
 

tern_test.go

@@ -361,7 +361,7 @@ version:  0 of 2`
 func TestConnStringCLIArg(t *testing.T) {
 	// Ensure database is in clean state
 	tern(t, "migrate", "-m", "testdata", "-c", "testdata/tern.conf", "-d", "0")
-	connString := os.Getenv("MIGRATE_TEST_CONN_STRING")
+	connString := os.Getenv("TERN_TEST_CONN_STRING")
 
 	output := tern(t, "status",
 		"-m", "testdata",

testdata/tern-conn-string.conf

@@ -1,2 +1,2 @@
 [database]
-conn_string = {{env "MIGRATE_TEST_CONN_STRING"}}
+conn_string = {{env "TERN_TEST_CONN_STRING"}}