diff --git a/HACKING.md b/HACKING.md
index 5ce72d8..8626305 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -6,7 +6,7 @@ core driver (`zsh-syntax-highlighting.zsh`), on the highlighters in the
 distribution, and on the test suite.  It does not target third-party
 highlighter authors (although they may find it an interesting read).
 
-The 'main' highlighter
+The `main` highlighter
 ----------------------
 
 The following function `pz` is useful when working on the `main` highlighting:
@@ -25,6 +25,25 @@ The following function `pz` is useful when working on the `main` highlighting:
 It prints, for each argument, its token breakdown, similar to how the main
 loop of the `main` highlighter sees it.
 
+Testing the `brackets` highlighter
+----------------------------------
+
+Since the test harness empties `ZSH_HIGHLIGHT_STYLES` and the `brackets`
+highlighter interrogates `ZSH_HIGHLIGHT_STYLES` to determine how to highlight,
+tests must set the `bracket-level-#` keys themselves.  For example:
+
+    ZSH_HIGHLIGHT_STYLES[bracket-level-1]=
+    ZSH_HIGHLIGHT_STYLES[bracket-level-2]=
+
+    BUFFER='echo ({x})'
+
+    expected_region_highlight=(
+      "6  6  bracket-level-1" # (
+      "7  7  bracket-level-2" # {
+      "9  9  bracket-level-2" # }
+      "10 10 bracket-level-1" # )
+    )
+
 IRC channel
 -----------
 
diff --git a/highlighters/brackets/test-data/mismatch-patentheses.zsh b/highlighters/brackets/test-data/mismatch-patentheses.zsh
index f0991b0..f40226f 100644
--- a/highlighters/brackets/test-data/mismatch-patentheses.zsh
+++ b/highlighters/brackets/test-data/mismatch-patentheses.zsh
@@ -27,6 +27,9 @@
 # vim: ft=zsh sw=2 ts=2 et
 # -------------------------------------------------------------------------------------------------
 
+ZSH_HIGHLIGHT_STYLES[bracket-level-1]=
+ZSH_HIGHLIGHT_STYLES[bracket-level-2]=
+
 BUFFER='echo ({x}]'
 
 expected_region_highlight=(
diff --git a/highlighters/brackets/test-data/nested-parentheses.zsh b/highlighters/brackets/test-data/nested-parentheses.zsh
index b3f531b..413394f 100644
--- a/highlighters/brackets/test-data/nested-parentheses.zsh
+++ b/highlighters/brackets/test-data/nested-parentheses.zsh
@@ -27,6 +27,10 @@
 # vim: ft=zsh sw=2 ts=2 et
 # -------------------------------------------------------------------------------------------------
 
+ZSH_HIGHLIGHT_STYLES[bracket-level-1]=
+ZSH_HIGHLIGHT_STYLES[bracket-level-2]=
+ZSH_HIGHLIGHT_STYLES[bracket-level-3]=
+
 BUFFER='echo $(echo ${(z)array})'
 
 expected_region_highlight=(
diff --git a/highlighters/brackets/test-data/simple-parentheses.zsh b/highlighters/brackets/test-data/simple-parentheses.zsh
index 3fc66df..186d0b9 100644
--- a/highlighters/brackets/test-data/simple-parentheses.zsh
+++ b/highlighters/brackets/test-data/simple-parentheses.zsh
@@ -27,6 +27,9 @@
 # vim: ft=zsh sw=2 ts=2 et
 # -------------------------------------------------------------------------------------------------
 
+ZSH_HIGHLIGHT_STYLES[bracket-level-1]=
+ZSH_HIGHLIGHT_STYLES[bracket-level-2]=
+
 BUFFER='echo ({x})'
 
 expected_region_highlight=(
diff --git a/highlighters/brackets/test-data/unclosed-patentheses.zsh b/highlighters/brackets/test-data/unclosed-patentheses.zsh
index e1a634a..941d092 100644
--- a/highlighters/brackets/test-data/unclosed-patentheses.zsh
+++ b/highlighters/brackets/test-data/unclosed-patentheses.zsh
@@ -27,6 +27,9 @@
 # vim: ft=zsh sw=2 ts=2 et
 # -------------------------------------------------------------------------------------------------
 
+ZSH_HIGHLIGHT_STYLES[bracket-level-1]=
+ZSH_HIGHLIGHT_STYLES[bracket-level-2]=
+
 BUFFER='echo ({x}'
 
 expected_region_highlight=(
diff --git a/highlighters/brackets/test-data/unclosed-patentheses2.zsh b/highlighters/brackets/test-data/unclosed-patentheses2.zsh
index 1a1937f..41b6836 100644
--- a/highlighters/brackets/test-data/unclosed-patentheses2.zsh
+++ b/highlighters/brackets/test-data/unclosed-patentheses2.zsh
@@ -27,6 +27,8 @@
 # vim: ft=zsh sw=2 ts=2 et
 # -------------------------------------------------------------------------------------------------
 
+ZSH_HIGHLIGHT_STYLES[bracket-level-1]=
+
 BUFFER='echo {x})'
 
 expected_region_highlight=(
diff --git a/tests/test-highlighting.zsh b/tests/test-highlighting.zsh
index d08237f..08912c1 100755
--- a/tests/test-highlighting.zsh
+++ b/tests/test-highlighting.zsh
@@ -153,6 +153,7 @@ fi
 
 # Process each test data file in test data directory.
 integer something_failed=0
+ZSH_HIGHLIGHT_STYLES=()
 for data_file in ${0:h:h}/highlighters/$1/test-data/*.zsh; do
   run_test "$data_file" | tee >($results_filter | ${0:A:h}/tap-colorizer.zsh) | grep -v '^not ok.*# TODO' | grep -Eq '^not ok|^ok.*# TODO' && (( something_failed=1 ))
   (( $pipestatus[1] )) && exit 2