Fix git dirty tests

These tests run in sequence in the same directory, they are not
isolated. Tests need to take account of changes to the directory state
made by previous tests.

tests/_pure_prompt_git_dirty.test.fish

@@ -28,54 +28,50 @@ end
 
 @test "_pure_prompt_git_dirty: untracked files in empty repo marked as dirty" (
     touch file.txt
+
     set --universal pure_symbol_git_dirty '*'
 
     _pure_prompt_git_dirty
 ) = '*'
 
 @test "_pure_prompt_git_dirty: staged files in empty repo marked as dirty" (
-    touch file.txt
+    echo "staged" >> file.txt
     git add file.txt
+
     set --universal pure_symbol_git_dirty '*'
 
     _pure_prompt_git_dirty
 ) = '*'
 
 @test "_pure_prompt_git_dirty: clean is not marked as dirty" (
-    touch init.txt
-    git add init.txt
-    git commit --quiet --message 'initial commit'
+    echo "clean" >> file.txt
+    git add file.txt
+    git commit --quiet --message 'commit staged files'
 
     set --universal pure_symbol_git_dirty '*'
 
     _pure_prompt_git_dirty
 ) = ''
 
 @test "_pure_prompt_git_dirty: untracked files mark git repo as dirty" (
-    touch init.txt
-    git add init.txt
-    git commit --quiet --message 'initial commit'
+    touch file_2.txt
 
-    touch file.txt
     set --universal pure_symbol_git_dirty '*'
 
     _pure_prompt_git_dirty
 ) = '*'
 
 @test "_pure_prompt_git_dirty: staged files mark git repo as dirty" (
-    touch init.txt
-    git add init.txt
-    git commit --quiet --message 'initial commit'
+    echo "staged" >> file_2.txt
+    git add file_2.txt
 
-    touch file.txt
-    git add file.txt
     set --universal pure_symbol_git_dirty '*'
 
     _pure_prompt_git_dirty
 ) = '*'
 
 @test "_pure_prompt_git_dirty: symbol is colorized" (
-    touch file.txt
+    echo "colorized" >> file.txt
 
     source (dirname (status filename))/../functions/_pure_set_color.fish # enable colors
     set --universal pure_symbol_git_dirty '*'