diff --git a/.gitignore b/.gitignore
index d72736e..11a7953 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,6 @@ HEAD
 src
 v*
 alias
+
+# For testing
+bak
diff --git a/README.markdown b/README.markdown
index 938e425..1982c94 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/83b0e53536d05a13501a9dc69b1a481158fedb24/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/test/fast/alias_creates_file b/test/fast/alias_creates_file
new file mode 100755
index 0000000..0ac4eb2
--- /dev/null
+++ b/test/fast/alias_creates_file
@@ -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/deactivate b/test/fast/deactivate
new file mode 100755
index 0000000..1dcef65
--- /dev/null
+++ b/test/fast/deactivate
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+. ../../nvm.sh
+nvm &&
+nvm deactivate &&
+! nvm
diff --git a/test/fast/ls/base should show all versions b/test/fast/ls/base should show all versions
new file mode 100755
index 0000000..dfba0da
--- /dev/null
+++ b/test/fast/ls/base should show all 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/ls/second number version b/test/fast/ls/second number version
new file mode 100755
index 0000000..5a3d450
--- /dev/null
+++ b/test/fast/ls/second number version	
@@ -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/multiple_aliases/all b/test/fast/multiple_aliases/all
new file mode 100755
index 0000000..42b1945
--- /dev/null
+++ b/test/fast/multiple_aliases/all
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+[ $(nvm alias | wc -l) = '10' ]
diff --git a/test/fast/multiple_aliases/setup_dir b/test/fast/multiple_aliases/setup_dir
new file mode 100755
index 0000000..3649602
--- /dev/null
+++ b/test/fast/multiple_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/multiple_aliases/some b/test/fast/multiple_aliases/some
new file mode 100755
index 0000000..78d0022
--- /dev/null
+++ b/test/fast/multiple_aliases/some
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+. ../../../nvm.sh
+[ $(nvm alias test1 | wc -l) = '2' ]
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/source b/test/fast/source
new file mode 100755
index 0000000..24f8efa
--- /dev/null
+++ b/test/fast/source
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+. ../../nvm.sh
+nvm
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/fast/unalias_removes_file b/test/fast/unalias_removes_file
new file mode 100755
index 0000000..f8ed49d
--- /dev/null
+++ b/test/fast/unalias_removes_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/uninstall b/test/fast/uninstall
new file mode 100755
index 0000000..ba1ddbb
--- /dev/null
+++ b/test/fast/uninstall
@@ -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/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