added tests for completion command (for bash and zsh)

tests/test_completion.py

@@ -0,0 +1,42 @@
+from test_pip import here, reset_env, run_pip, pyversion, lib_py
+from test_pip import write_file
+
+def test_completion_for_bash():
+    """
+    Test getting completion for bash shell
+    """
+    reset_env()
+    bash_completion = """\
+_pip_completion()
+{
+    COMPREPLY=( $( COMP_WORDS="${COMP_WORDS[*]}" \\
+                   COMP_CWORD=$COMP_CWORD \\
+                   PIP_AUTO_COMPLETE=1 $1 ) )
+}
+complete -o default -F _pip_completion pip"""
+
+    result = run_pip('completion', '--bash')
+    assert bash_completion in result.stdout, "bash completion is wrong"
+
+
+
+def test_completion_for_zsh():
+    """
+    Test getting completion for zsh shell
+    """
+    reset_env()
+    zsh_completion = """\
+function _pip_completion {
+  local words cword
+  read -Ac words
+  read -cn cword
+  reply=( $( COMP_WORDS="$words[*]" \\ 
+             COMP_CWORD=$(( cword-1 )) \\
+             PIP_AUTO_COMPLETE=1 $words[1] ) )
+}
+compctl -K _pip_completion pip"""
+
+    result = run_pip('completion', '--zsh')
+    assert zsh_completion in result.stdout, "zsh completion is wrong"
+
+