Change behaviour significantly:

-Start at current directory
-Look inside all sub-directories to see if there is a bin/activate.fish script
-If not found, look in the parent directory, and continue up the file path until one is found, or give up

Covers cases like:
-Virtual environment is in a .venv or venv folder (any folder name is supportd) in the current working directory
-Virtual environment is in a parent folder of the current working directory
-Virtual environment is in the current working directory

init.fish

@@ -9,30 +9,51 @@ if status is-interactive
         and set -g autovenv_enable "yes"
 end
 
+# Gets particular elements from an array
+# eg. $some_array | select 1 3
+# Returns the first and 3rd elements
+function select
+  read --local --array --null arr
+  echo $arr[$argv]
+end
+
 ## AutoVenv Function
 # Activates on directory changes.
 function autovenv --on-variable PWD -d "Automatic activation of Python virtual environments"
     # Check for the enable flag and make sure we're running interactive, if not return.
     test ! "$autovenv_enable" = "yes"
         or not status is-interactive
         and return
-    # We start by splitting our CWD path into individual elements and iterating over each element.
-    # If our CWD is `/opt/my/hovercraft/eels` we split it into a variable containing 4 entries:
-    # `opt`, `my`, `hovercraft` and `eels`. We then build back up the path by iterating over the list
-    # and adding each element to the previous one. (We start with `/opt`, then `/opt/my` and so on.)
-    # During each run through the loop we test for a sub-directory/file called `bin/activate.fish`. If a
-    # venv is found we go ahead and break out of the loop, otherwise continue. We go through all of this
-    # instead of just checking the CWD to handle cases where the user moves into a sub-directory of the venv.
-    for _dir in (string split -n '/' "$PWD")
-        set -l _tree "$_tree/$_dir"
-        if test -e "$_tree/bin/activate.fish"
-            set _source "$_tree/bin/activate.fish"
-            if test "$autovenv_announce" = "yes"
-                set -g __autovenv_old $__autovenv_new
-                set -g __autovenv_new (basename $_tree)
+    # Start at PWD (prsent working directory, see if there is a subfolder that contains bin/activate.fish
+    # ie. start at $PWD/<any subdir>/bin/activate.fish
+    # If that doesn't exist, try $PWD/../<any subdir>/bin/activate.fish
+    # Keep going until we cannot go any further
+    set -l _tree "$PWD/."
+    set -l _done false
+    while true
+        set _tree (string split -r -m 1 -n '/' "$_tree" | select 1)
+        if ! string match -q -- "/*" $_tree 
+            # This is a hack to stop when we have ascended all the way up to the top of the tree.
+            # The string split command above eventually returns something like "home" when it tries
+            # to split "/home". So the lack of a slash is what we do to tell us that "it's time to stop"
+            break
+        end
+        for _venv_dir in (find "$_tree" -maxdepth 1 -type d)
+            if test -e "$_venv_dir/bin/activate.fish"
+                set _source "$_venv_dir/bin/activate.fish"
+                if test "$autovenv_announce" = "yes"
+                    set -g __autovenv_old $__autovenv_new
+                    set -g __autovenv_new (basename $_tree)
+                    set venv_dir $_venv_dir
+                end
+                set _done true
+                break
             end
+        end
+        if $_done
             break
         end
+
     end
     # If we're *not* in an active venv and the venv source dir exists we activate it and return.
     if test -z "$VIRTUAL_ENV" -a -e "$_source"
@@ -43,7 +64,7 @@ function autovenv --on-variable PWD -d "Automatic activation of Python virtual e
     # Next we check to see if we're already in an active venv. If so we proceed with further tests.
     else if test -n "$VIRTUAL_ENV"
         # Check to see if our CWD is inside the venv directory.
-        set _dir (string match -n "$VIRTUAL_ENV*" "$PWD")
+        set _dir (string match -n "$VIRTUAL_ENV*" "$venv_dir")
         # If we're no longer inside the venv dirctory deactivate it and return.
         if test -z "$_dir" -a ! -e "$_source"
             deactivate
@@ -62,4 +83,4 @@ function autovenv --on-variable PWD -d "Automatic activation of Python virtual e
         end
     end
 end
-################################################################################
+################################################################################