diff --git a/.travis.yml b/.travis.yml
index 3daa25d3..ccefa809 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,9 +17,9 @@ script:
 # possible issues with MANIFEST.in
 - pushd tests;
   if [ ${REPO_TYPE} == "r" ]; then
-    travis_wait pytest --cov repo2docker -v ${REPO_TYPE};
+    travis_wait pytest --cov repo2docker -v ${REPO_TYPE} || exit 1;
   else
-    travis_retry pytest --cov repo2docker -v ${REPO_TYPE};
+    travis_retry pytest --cov repo2docker -v ${REPO_TYPE} || exit 1;
   fi;
   popd;
 - pip install -r docs/doc-requirements.txt
diff --git a/tests/base/node10/README.md b/tests/base/node10/README.md
index 3c1ea14d..a68e33a7 100644
--- a/tests/base/node10/README.md
+++ b/tests/base/node10/README.md
@@ -1 +1 @@
-Test that node 10 is installed and runnable.
+Test that node 10 and npm 6 are installed and runnable.
diff --git a/tests/base/node10/verify b/tests/base/node10/verify
index 2a203796..2ededbc4 100755
--- a/tests/base/node10/verify
+++ b/tests/base/node10/verify
@@ -2,6 +2,9 @@
 
 set -e
 which node
+node --version
 node --version | grep v10
+
 which npm
-npm --version | grep 6.2
+npm --version
+npm --version | grep 6.4
diff --git a/tests/conftest.py b/tests/conftest.py
index f4031efe..4e05a690 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -95,11 +95,10 @@ class Repo2DockerTest(pytest.Function):
 class LocalRepo(pytest.File):
     def collect(self):
         yield Repo2DockerTest(
-            self.fspath.basename, self,
+            'build', self,
             args=[
                 '--appendix', 'RUN echo "appendix" > /tmp/appendix',
                 self.fspath.dirname,
-                './verify',
             ],
         )
         yield Repo2DockerTest(
@@ -107,6 +106,7 @@ class LocalRepo(pytest.File):
             args=[
                 '--appendix', 'RUN echo "appendix" > /tmp/appendix',
                 self.fspath.dirname,
+                './verify',
             ],
         )
 
diff --git a/tests/venv/py2-with-kernel-requirements/verify b/tests/venv/py2-with-kernel-requirements/verify
old mode 100644
new mode 100755
diff --git a/tests/venv/start/postBuild/README.rst b/tests/venv/start/postBuild/README.rst
index 1a9851f3..ecfd428e 100644
--- a/tests/venv/start/postBuild/README.rst
+++ b/tests/venv/start/postBuild/README.rst
@@ -1,8 +1,5 @@
-System - Post-build scripts
----------------------------
-
-It is possible to run scripts after you've built the environment specified in
-your other files. This could be used to, for example, download data or run
-some configuration scripts.
-
-In this example, we download and install a Jupyter Notebook extension.
+postBuild and start
+-------------------
+
+This test checks that we can use a postBuild and start script
+at the same time.
diff --git a/tests/venv/start/postBuild/postBuild b/tests/venv/start/postBuild/postBuild
index 28b840f0..dbf15529 100755
--- a/tests/venv/start/postBuild/postBuild
+++ b/tests/venv/start/postBuild/postBuild
@@ -1,2 +1,6 @@
 #!/bin/bash
+
+# this value should not be visible in `verify`
+export TEST_START_VAR="var is set by postBuild"
+
 jupyter nbextension enable --py --sys-prefix ipyleaflet
diff --git a/tests/venv/start/postBuild/start b/tests/venv/start/postBuild/start
new file mode 100644
index 00000000..b8354e90
--- /dev/null
+++ b/tests/venv/start/postBuild/start
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+export TEST_START_VAR="var is set"
+exec "$@"
diff --git a/tests/venv/start/postBuild/verify b/tests/venv/start/postBuild/verify
index cc0d9ea7..2daa9539 100755
--- a/tests/venv/start/postBuild/verify
+++ b/tests/venv/start/postBuild/verify
@@ -2,7 +2,8 @@
 set -euo pipefail
 jupyter nbextension list | grep 'jupyter-leaflet' | grep enabled
 
-if [ "$TEST_START_VAR" != "var is set" ]
+# set value of TEST_START_VAR to empty string when it is not defined
+if [ "${TEST_START_VAR:-}" != "var is set" ]
 then
   echo "TEST_START_VAR is not set"
   exit 1
diff --git a/tests/venv/start/start-script/verify b/tests/venv/start/start-script/verify
old mode 100644
new mode 100755
index 8422ceba..b466ab08
--- a/tests/venv/start/start-script/verify
+++ b/tests/venv/start/start-script/verify
@@ -1,7 +1,8 @@
 #!/bin/bash
 set -euo pipefail
 
-if [ "$TEST_START_VAR" != "var is set" ]
+# set value of TEST_START_VAR to empty string when it is not defined
+if [ "${TEST_START_VAR:-}" != "var is set" ]
 then
   echo "TEST_START_VAR is not set"
   exit 1