diff --git a/t/t1505-rev-parse-last.sh b/t/t1505-rev-parse-last.sh
index d709ecf8df..4969edb314 100755
--- a/t/t1505-rev-parse-last.sh
+++ b/t/t1505-rev-parse-last.sh
@@ -32,32 +32,24 @@ test_expect_success 'setup' '
 #
 # and 'side' should be the last branch
 
-test_rev_equivalent () {
-
-	git rev-parse "$1" > expect &&
-	git rev-parse "$2" > output &&
-	test_cmp expect output
-
-}
-
 test_expect_success '@{-1} works' '
-	test_rev_equivalent side @{-1}
+	test_cmp_rev side @{-1}
 '
 
 test_expect_success '@{-1}~2 works' '
-	test_rev_equivalent side~2 @{-1}~2
+	test_cmp_rev side~2 @{-1}~2
 '
 
 test_expect_success '@{-1}^2 works' '
-	test_rev_equivalent side^2 @{-1}^2
+	test_cmp_rev side^2 @{-1}^2
 '
 
 test_expect_success '@{-1}@{1} works' '
-	test_rev_equivalent side@{1} @{-1}@{1}
+	test_cmp_rev side@{1} @{-1}@{1}
 '
 
 test_expect_success '@{-2} works' '
-	test_rev_equivalent master @{-2}
+	test_cmp_rev master @{-2}
 '
 
 test_expect_success '@{-3} fails' '
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 32fdc9938e..8462be1db6 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -29,12 +29,6 @@ Initial setup:
 
 . "$TEST_DIRECTORY"/lib-rebase.sh
 
-test_cmp_rev () {
-	git rev-parse --verify "$1" >expect.rev &&
-	git rev-parse --verify "$2" >actual.rev &&
-	test_cmp expect.rev actual.rev
-}
-
 set_fake_editor
 
 # WARNING: Modifications to the initial repository can change the SHA ID used
diff --git a/t/t3507-cherry-pick-conflict.sh b/t/t3507-cherry-pick-conflict.sh
index c82f7210c4..223b98433c 100755
--- a/t/t3507-cherry-pick-conflict.sh
+++ b/t/t3507-cherry-pick-conflict.sh
@@ -11,12 +11,6 @@ test_description='test cherry-pick and revert with conflicts
 
 . ./test-lib.sh
 
-test_cmp_rev () {
-	git rev-parse --verify "$1" >expect.rev &&
-	git rev-parse --verify "$2" >actual.rev &&
-	test_cmp expect.rev actual.rev
-}
-
 pristine_detach () {
 	git checkout -f "$1^0" &&
 	git read-tree -u --reset HEAD &&
diff --git a/t/t3508-cherry-pick-many-commits.sh b/t/t3508-cherry-pick-many-commits.sh
index 340afc760d..4e7136b837 100755
--- a/t/t3508-cherry-pick-many-commits.sh
+++ b/t/t3508-cherry-pick-many-commits.sh
@@ -5,15 +5,11 @@ test_description='test cherry-picking many commits'
 . ./test-lib.sh
 
 check_head_differs_from() {
-	head=$(git rev-parse --verify HEAD) &&
-	arg=$(git rev-parse --verify "$1") &&
-	test "$head" != "$arg"
+	! test_cmp_rev HEAD "$1"
 }
 
 check_head_equals() {
-	head=$(git rev-parse --verify HEAD) &&
-	arg=$(git rev-parse --verify "$1") &&
-	test "$head" = "$arg"
+	test_cmp_rev HEAD "$1"
 }
 
 test_expect_success setup '
diff --git a/t/t3510-cherry-pick-sequence.sh b/t/t3510-cherry-pick-sequence.sh
index b5fb527b2e..7b7a89dbd5 100755
--- a/t/t3510-cherry-pick-sequence.sh
+++ b/t/t3510-cherry-pick-sequence.sh
@@ -24,12 +24,6 @@ pristine_detach () {
 	git clean -d -f -f -q -x
 }
 
-test_cmp_rev () {
-	git rev-parse --verify "$1" >expect.rev &&
-	git rev-parse --verify "$2" >actual.rev &&
-	test_cmp expect.rev actual.rev
-}
-
 test_expect_success setup '
 	git config advice.detachedhead false &&
 	echo unrelated >unrelated &&
diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
index 72e28ee535..3e0e15fb3e 100755
--- a/t/t6030-bisect-porcelain.sh
+++ b/t/t6030-bisect-porcelain.sh
@@ -676,9 +676,7 @@ test_expect_success 'bisect fails if tree is broken on trial commit' '
 check_same()
 {
 	echo "Checking $1 is the same as $2" &&
-	git rev-parse "$1" > expected.same &&
-	git rev-parse "$2" > expected.actual &&
-	test_cmp expected.same expected.actual
+	test_cmp_rev "$1" "$2"
 }
 
 test_expect_success 'bisect: --no-checkout - start commit bad' '
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 22a4f8fb64..fa62d010f6 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -602,6 +602,13 @@ test_cmp() {
 	$GIT_TEST_CMP "$@"
 }
 
+# Tests that its two parameters refer to the same revision
+test_cmp_rev () {
+	git rev-parse --verify "$1" >expect.rev &&
+	git rev-parse --verify "$2" >actual.rev &&
+	test_cmp expect.rev actual.rev
+}
+
 # Print a sequence of numbers or letters in increasing order.  This is
 # similar to GNU seq(1), but the latter might not be available
 # everywhere (and does not do letters).  It may be used like: