diff --git a/.gitignore b/.gitignore
index d72736e..32d72b6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,7 @@ HEAD
 src
 v*
 alias
+
+# For testing
+bak
+.urchin.log
diff --git a/README.markdown b/README.markdown
index 938e425..f8c186d 100644
--- a/README.markdown
+++ b/README.markdown
@@ -57,6 +57,30 @@ The above copyright notice and this permission notice shall be included in all c
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+## Running tests
+Tests are written in [Urchin](http://www.urchin.sh). Install Urchin like so.
+
+    wget -O /usr/local/bin https://raw.github.com/scraperwiki/urchin/0c6837cfbdd0963903bf0463b05160c2aecc22ef/urchin
+    chmod +x /usr/local/bin/urchin
+
+(Or put it some other place in your PATH.)
+
+There are slow tests and fast tests. The slow tests do things like install node
+and check that the right versions are used. The fast tests fake this to test
+things like aliases and uninstalling. From the root of the nvm git repository,
+run the fast tests like this.
+
+    urchin test/fast
+
+Run the slow tests like this.
+
+    urchin test/slow
+
+Run all of the tests like this
+
+    urchin test
+
+Nota bene: Avoid running nvm while the tests are running.
 
 ## Bash completion
 
diff --git a/nvm.sh b/nvm.sh
index 544c176..2bed1f5 100755
--- a/nvm.sh
+++ b/nvm.sh
@@ -12,7 +12,7 @@ fi
 
 # Make zsh glob matching behave same as bash
 # This fixes the "zsh: no matches found" errors
-if [[ `which unsetopt 2>/dev/null` ]]; then
+if [ ! -z "$(which unsetopt 2>/dev/null)" ]; then
     unsetopt nomatch 2>/dev/null
 fi
 
diff --git "a/test/fast/Aliases/Running \"nvm alias <aliasname>\" should list but one alias." "b/test/fast/Aliases/Running \"nvm alias <aliasname>\" should list but one alias."
new file mode 100755
index 0000000..78d0022
--- /dev/null
+++ "b/test/fast/Aliases/Running \"nvm alias <aliasname>\" should list but one alias."	
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+[ $(nvm alias test1 | wc -l) = '2' ]
diff --git "a/test/fast/Aliases/Running \"nvm alias\" should list all aliases." "b/test/fast/Aliases/Running \"nvm alias\" should list all aliases."
new file mode 100755
index 0000000..42b1945
--- /dev/null
+++ "b/test/fast/Aliases/Running \"nvm alias\" should list all aliases."	
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+[ $(nvm alias | wc -l) = '10' ]
diff --git a/test/fast/Aliases/setup_dir b/test/fast/Aliases/setup_dir
new file mode 100755
index 0000000..3649602
--- /dev/null
+++ b/test/fast/Aliases/setup_dir
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+for i in $(seq 1 10)
+  do
+  echo v0.0.$i > ../../../alias/test$i
+done
diff --git "a/test/fast/Listing versions/Running \"nvm ls 0.2\" should display only 0.2.x versions." "b/test/fast/Listing versions/Running \"nvm ls 0.2\" should display only 0.2.x versions."
new file mode 100755
index 0000000..5a3d450
--- /dev/null
+++ "b/test/fast/Listing versions/Running \"nvm ls 0.2\" should display only 0.2.x versions."	
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+mkdir ../../../v0.1.3
+mkdir ../../../v0.2.3
+
+. ../../../nvm.sh
+
+# The result should contain only the appropriate version numbers.
+nvm ls 0.2 | grep v0.2.3 &&
+nvm ls 0.1 | grep -v v0.2.3
diff --git "a/test/fast/Listing versions/Running \"nvm ls\" should display all installed versions." "b/test/fast/Listing versions/Running \"nvm ls\" should display all installed versions."
new file mode 100755
index 0000000..dfba0da
--- /dev/null
+++ "b/test/fast/Listing versions/Running \"nvm ls\" should display all installed versions."	
@@ -0,0 +1,14 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+
+mkdir ../../../v0.0.{1,3,9}
+mkdir ../../../v0.3.{1,3,9}
+
+# The result should contain the version numbers.
+nvm ls | grep v0.0.1 &&
+nvm ls | grep v0.0.3 &&
+nvm ls | grep v0.0.9 &&
+nvm ls | grep v0.3.1 &&
+nvm ls | grep v0.3.3 &&
+nvm ls | grep v0.3.9
diff --git "a/test/fast/Running \"nvm alias\" should create a file in the alias directory." "b/test/fast/Running \"nvm alias\" should create a file in the alias directory."
new file mode 100755
index 0000000..0ac4eb2
--- /dev/null
+++ "b/test/fast/Running \"nvm alias\" should create a file in the alias directory."	
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+. ../../nvm.sh
+nvm alias test v0.1.2
+[ $(cat ../../alias/test) = 'v0.1.2' ]
diff --git "a/test/fast/Running \"nvm deactivate\" should unset the nvm environment variables." "b/test/fast/Running \"nvm deactivate\" should unset the nvm environment variables."
new file mode 100755
index 0000000..1dcef65
--- /dev/null
+++ "b/test/fast/Running \"nvm deactivate\" should unset the nvm environment variables."	
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+. ../../nvm.sh
+nvm &&
+nvm deactivate &&
+! nvm
diff --git "a/test/fast/Running \"nvm unalias\" should remove the alias file." "b/test/fast/Running \"nvm unalias\" should remove the alias file."
new file mode 100755
index 0000000..f8ed49d
--- /dev/null
+++ "b/test/fast/Running \"nvm unalias\" should remove the alias file."	
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+echo v0.1.2 > ../../alias/test
+. ../../nvm.sh
+nvm unalias test
+! [ -e ../../alias/test ]
diff --git "a/test/fast/Running \"nvm uninstall\" should remove the appropriate directory." "b/test/fast/Running \"nvm uninstall\" should remove the appropriate directory."
new file mode 100755
index 0000000..ba1ddbb
--- /dev/null
+++ "b/test/fast/Running \"nvm uninstall\" should remove the appropriate directory."	
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+cd ../..
+mkdir v0.0.1
+mkdir src/node-v0.0.1
+
+. ./nvm.sh
+nvm uninstall v0.0.1
+
+[ ! -d 'v0.0.1' ] && [ ! -d 'src/node-v0.0.1' ]
diff --git a/test/fast/Sourcing nvm.sh should make the nvm command available. b/test/fast/Sourcing nvm.sh should make the nvm command available.
new file mode 100755
index 0000000..24f8efa
--- /dev/null
+++ b/test/fast/Sourcing nvm.sh should make the nvm command available.	
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+. ../../nvm.sh
+nvm
diff --git a/test/fast/setup b/test/fast/setup
new file mode 100755
index 0000000..b433b5c
--- /dev/null
+++ b/test/fast/setup
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+(
+  cd ../..
+
+  # Back up
+  rm -Rf v* src alias
+  mkdir src alias
+)
diff --git a/test/fast/setup_dir b/test/fast/setup_dir
new file mode 100755
index 0000000..1bba6c2
--- /dev/null
+++ b/test/fast/setup_dir
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+(
+  cd ../..
+
+  # Back up
+  mkdir -p bak
+  mv v* src alias bak || sleep 0s
+)
diff --git a/test/fast/teardown b/test/fast/teardown
new file mode 100755
index 0000000..954850f
--- /dev/null
+++ b/test/fast/teardown
@@ -0,0 +1,7 @@
+#!/bin/sh
+
+# Remove temporary files
+(
+  cd ../..
+  rm -fR v* src alias
+)
diff --git a/test/fast/teardown_dir b/test/fast/teardown_dir
new file mode 100755
index 0000000..1e6d005
--- /dev/null
+++ b/test/fast/teardown_dir
@@ -0,0 +1,13 @@
+#!/bin/sh
+
+(
+  cd ../..
+
+  # Restore
+  if [ -d bak ]
+    then
+    mv bak/* . || sleep 0s
+    rmdir bak
+  fi
+  mkdir -p src alias
+)
diff --git a/test/slow/install b/test/slow/install
new file mode 100755
index 0000000..460627b
--- /dev/null
+++ b/test/slow/install
@@ -0,0 +1,14 @@
+#!/bin/sh
+
+set -e
+. ../../nvm.sh
+
+# Remove the stuff we're clobbering.
+[ -e ../../v0.6.14 ] && rm -R ../../v0.6.14
+
+# Install
+nvm install 0.6.14
+
+# Check
+[ -d ../../v0.6.14 ]
+nvm run v0.6.14 --version | grep v0.6.14