diff --git a/tests/functional/Dockerfile-ubuntu b/tests/functional/Dockerfile-ubuntu
index cd4cb95..1de87c0 100644
--- a/tests/functional/Dockerfile-ubuntu
+++ b/tests/functional/Dockerfile-ubuntu
@@ -9,59 +9,86 @@ WORKDIR /opt/auto-click-auto
 
 RUN pip install -e .
 
+# Test adding autocompletion for bash and fish
 FROM base_test_env as test_example_1
 RUN echo "Current login shell is $SHELL" \
+    && touch ~/.zshrc \
     && echo "John Doe" | python3 examples/example_1.py \
-    && grep 'eval "\$(_EXAMPLE_1_COMPLETE=bash_source example-1)"' ~/.bashrc \
+    # Check that configuration has been added for bash
+    && grep 'command -v example-1 > /dev/null 2>&1 && eval "\$(_EXAMPLE_1_COMPLETE=bash_source example-1)"' ~/.bashrc \
     && echo "~/.bashrc file is correct..." \
-    && grep '_EXAMPLE_1_COMPLETE=fish_source example-1 | source' ~/.config/fish/completions/example-1.fish \
+    # Check that configuration has been added for fish
+    && grep 'command -v example-1 > /dev/null 2>&1 && _EXAMPLE_1_COMPLETE=fish_source example-1 | source' ~/.config/fish/completions/example-1.fish \
     && echo "fish config file is correct..." \
-    && touch ~/.zshrc \
-    && ! grep -q 'eval "\$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"' ~/.zshrc || { echo "Completion added"; exit 1; }
+    # Check that no configuration has been added for zsh
+    && ! grep -q 'command -v example-1 > /dev/null 2>&1 && eval "\$(_EXAMPLE_1_COMPLETE=zsh_source example-1)"' ~/.zshrc || { echo "Completion should not haven be added"; exit 1; }
 
+# Test adding autocompletion with default option and autodetect with bash
 FROM base_test_env as test_example_2_bash
 RUN echo "Current login shell is $SHELL" \
+    && touch ~/.zshrc \
     # We need to export the env variable otherwise we can't get it with
     # Python's `os.environ["SHELL"]`.
     && export SHELL=/bin/bash \
+    # Check that configuration has been added for bash
+    && cp tests/functional/config_files/.bashrc-test-old ~/.bashrc \
     && python3 examples/example_2.py --autocomplete \
-    && grep 'eval "\$(_EXAMPLE_2_COMPLETE=bash_source example-2)"' ~/.bashrc \
+    && grep 'command -v example-2 > /dev/null 2>&1 && eval "\$(_EXAMPLE_2_COMPLETE=bash_source example-2)"' ~/.bashrc \
+    && diff ~/.bashrc tests/functional/config_files/.bashrc-test-new \
     && echo "~/.bashrc file is correct..." \
-    && touch ~/.zshrc \
-    && ! grep -q 'eval "\$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"' ~/.zshrc || { echo "Completion added"; exit 1; } \
-    && if [ -e "~/.config/fish/completions/example-2.fish" ]; then echo "File exists"; exit 1; fi
+    # Check that no configuration has been added for zsh
+    && ! grep -q 'command -v example-2 > /dev/null 2>&1 && eval "\$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"' ~/.zshrc || { echo "Completion should not haven be added"; exit 1; } \
+    # Check that no configuration has been added for fish
+    && if [ -e "~/.config/fish/completions/example-2.fish" ]; then echo "File should not exist"; exit 1; fi
 
+# Test adding autocompletion with default option and autodetect with zsh
 FROM base_test_env as test_example_2_zsh
 RUN echo "Current login shell is $SHELL" \
     && touch ~/.zshrc \
     # We need to export the env variable otherwise we can't get it with
     # Python's `os.environ["SHELL"]`.
     && export SHELL=/bin/zsh \
+    # Check that configuration has been added for zsh
+    && cp tests/functional/config_files/.zshrc-test-old ~/.zshrc \
     && python3 examples/example_2.py --autocomplete \
-    && grep 'eval "\$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"' ~/.zshrc \
+    && grep 'command -v example-2 > /dev/null 2>&1 && eval "\$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"' ~/.zshrc \
+    && diff ~/.zshrc tests/functional/config_files/.zshrc-test-new \
     && echo "~/.zshrc file is correct..." \
-    && ! grep -q 'eval "\$(_EXAMPLE_2_COMPLETE=bash_source example-2)"' ~/.bashrc || { echo "Completion added"; exit 1; } \
-    && if [ -e "~/.config/fish/completions/example-2.fish" ]; then echo "File exists"; exit 1; fi
+    # Check that no configuration has been added for bash
+    && ! grep -q 'command -v example-2 > /dev/null 2>&1 && eval "\$(_EXAMPLE_2_COMPLETE=bash_source example-2)"' ~/.bashrc || { echo "Completion should not haven be added"; exit 1; } \
+    # Check that no configuration has been added for fish
+    && if [ -e "~/.config/fish/completions/example-2.fish" ]; then echo "File should not exist"; exit 1; fi
 
+# Test adding autocompletion with default option and autodetect with fish
 FROM base_test_env as test_example_2_fish
 RUN echo "Current login shell is $SHELL" \
     && touch ~/.zshrc \
+    && mkdir -p ~/.config/fish/completions/ \
     # We need to export the env variable otherwise we can't get it with
     # Python's `os.environ["SHELL"]`.
     && export SHELL=/usr/bin/fish \
+    # Check that configuration has been added for fish
+    && cp tests/functional/config_files/.fish-test-old ~/.config/fish/completions/example-2.fish \
     && python3 examples/example_2.py --autocomplete \
-    && grep '_EXAMPLE_2_COMPLETE=fish_source example-2 | source' ~/.config/fish/completions/example-2.fish \
+    && diff ~/.config/fish/completions/example-2.fish tests/functional/config_files/.fish-test-new \
+    && grep 'command -v example-2 > /dev/null 2>&1 && _EXAMPLE_2_COMPLETE=fish_source example-2 | source' ~/.config/fish/completions/example-2.fish \
     && echo "fish config file is correct..." \
-    && ! grep -q 'eval "\$(_EXAMPLE_2_COMPLETE=bash_source example-2)"' ~/.bashrc || { echo "Completion added"; exit 1; } \
-    && ! grep -q 'eval "\$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"' ~/.zshrc || { echo "Completion added"; exit 1; }
+    # Check that no configuration has been added for bash
+    && ! grep -q 'command -v example-2 > /dev/null 2>&1 && eval "\$(_EXAMPLE_2_COMPLETE=bash_source example-2)"' ~/.bashrc || { echo "Completion should not haven be added"; exit 1; } \
+    # Check that no configuration has been added for zsh
+    && ! grep -q 'command -v example-2 > /dev/null 2>&1 && eval "\$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"' ~/.zshrc || { echo "Completion should not haven be added"; exit 1; }
 
+# Test adding autocompletion for bash, zsh, fish
 FROM base_test_env as test_example_3
 RUN echo "Current login shell is $SHELL" \
     && touch ~/.zshrc \
     && python3 examples/example_3.py config shell-completion \
-    && grep 'eval "\$(_EXAMPLE_3_COMPLETE=bash_source example-3)"' ~/.bashrc \
+    # Check that configuration has been added for bash
+    && grep 'command -v example-3 > /dev/null 2>&1 && eval "\$(_EXAMPLE_3_COMPLETE=bash_source example-3)"' ~/.bashrc \
     && echo "~/.bashrc file is correct..." \
-    && grep 'eval "\$(_EXAMPLE_3_COMPLETE=zsh_source example-3)"' ~/.zshrc \
+    # Check that configuration has been added for zsh
+    && grep 'command -v example-3 > /dev/null 2>&1 && eval "\$(_EXAMPLE_3_COMPLETE=zsh_source example-3)"' ~/.zshrc \
     && echo "~/.zshrc file is correct..." \
-    && grep '_EXAMPLE_3_COMPLETE=fish_source example-3 | source' ~/.config/fish/completions/example-3.fish \
+    # Check that configuration has been added for fish
+    && grep 'command -v example-3 > /dev/null 2>&1 && _EXAMPLE_3_COMPLETE=fish_source example-3 | source' ~/.config/fish/completions/example-3.fish \
     && echo "fish config file is correct..."   
diff --git a/tests/functional/config_files/.bashrc-test-new b/tests/functional/config_files/.bashrc-test-new
new file mode 100644
index 0000000..c465bd6
--- /dev/null
+++ b/tests/functional/config_files/.bashrc-test-new
@@ -0,0 +1,17 @@
+# Example .bashrc config file
+
+# If not running interactively, don't do anything
+case $- in
+    *i*) ;;
+      *) return;;
+esac
+
+
+
+# Define some colors first:
+red='\e[0;31m'
+RED='\e[1;31m'
+blue='\e[0;34m'
+
+# Shell completion configuration for the Click Python package
+command -v example-2 > /dev/null 2>&1 && eval "$(_EXAMPLE_2_COMPLETE=bash_source example-2)"
\ No newline at end of file
diff --git a/tests/functional/config_files/.bashrc-test-old b/tests/functional/config_files/.bashrc-test-old
new file mode 100644
index 0000000..7d2e5ce
--- /dev/null
+++ b/tests/functional/config_files/.bashrc-test-old
@@ -0,0 +1,16 @@
+# Example .bashrc config file
+
+# If not running interactively, don't do anything
+case $- in
+    *i*) ;;
+      *) return;;
+esac
+
+
+# Shell completion configuration for the Click Python package
+eval "$(_EXAMPLE_2_COMPLETE=bash_source example-2)"
+
+# Define some colors first:
+red='\e[0;31m'
+RED='\e[1;31m'
+blue='\e[0;34m'
\ No newline at end of file
diff --git a/tests/functional/config_files/.fish-test-new b/tests/functional/config_files/.fish-test-new
new file mode 100644
index 0000000..78c0c52
--- /dev/null
+++ b/tests/functional/config_files/.fish-test-new
@@ -0,0 +1,6 @@
+# Example fish config file
+
+
+
+# Shell completion configuration for the Click Python package
+command -v example-2 > /dev/null 2>&1 && _EXAMPLE_2_COMPLETE=fish_source example-2 | source
\ No newline at end of file
diff --git a/tests/functional/config_files/.fish-test-old b/tests/functional/config_files/.fish-test-old
new file mode 100644
index 0000000..2c18b5d
--- /dev/null
+++ b/tests/functional/config_files/.fish-test-old
@@ -0,0 +1,4 @@
+# Example fish config file
+
+# Shell completion configuration for the Click Python package
+_EXAMPLE_2_COMPLETE=fish_source example-2 | source
\ No newline at end of file
diff --git a/tests/functional/config_files/.zshrc-test-new b/tests/functional/config_files/.zshrc-test-new
new file mode 100644
index 0000000..af1a9e6
--- /dev/null
+++ b/tests/functional/config_files/.zshrc-test-new
@@ -0,0 +1,18 @@
+# Example .zshrc config file
+
+# If not running interactively, don't do anything
+case $- in
+    *i*) ;;
+      *) return;;
+esac
+
+
+
+
+# Define some colors first:
+red='\e[0;31m'
+RED='\e[1;31m'
+blue='\e[0;34m'
+
+# Shell completion configuration for the Click Python package
+command -v example-2 > /dev/null 2>&1 && eval "$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"
\ No newline at end of file
diff --git a/tests/functional/config_files/.zshrc-test-old b/tests/functional/config_files/.zshrc-test-old
new file mode 100644
index 0000000..780153d
--- /dev/null
+++ b/tests/functional/config_files/.zshrc-test-old
@@ -0,0 +1,17 @@
+# Example .zshrc config file
+
+# If not running interactively, don't do anything
+case $- in
+    *i*) ;;
+      *) return;;
+esac
+
+
+
+# Shell completion configuration for the Click Python package
+eval "$(_EXAMPLE_2_COMPLETE=zsh_source example-2)"
+
+# Define some colors first:
+red='\e[0;31m'
+RED='\e[1;31m'
+blue='\e[0;34m'
\ No newline at end of file