4 files changed, 73 insertions, 39 deletions
diff --git a/assert/assert.go b/assert/assert.go
index a13c15e..fe725f6 100644
--- a/assert/assert.go
+++ b/assert/assert.go
@@ -5,38 +5,9 @@
 // Each assertion in this package returns a bool to indicate whether the check succeeded, and logs a t.Error() when the check does not succeed.
 package assert
 
-import (
-	"context"
-	"io"
-	"testing"
-)
+import "go.xyrillian.de/gg/testcapture"
 
 // TestingTB contains all the public functions of [testing.TB] (as of Go 1.26).
-// Functions in this package use this type instead of [testing.TB] because the capture device used by package testcapture cannot implement [testing.TB]: It contains methods that are private to the standard library.
-type TestingTB interface {
-	ArtifactDir() string
-	Attr(key, value string)
-	Chdir(dir string)
-	Cleanup(func())
-	Context() context.Context
-	Error(args ...any)
-	Errorf(format string, args ...any)
-	Fail()
-	Failed() bool
-	FailNow()
-	Fatal(args ...any)
-	Fatalf(format string, args ...any)
-	Helper()
-	Log(args ...any)
-	Logf(format string, args ...any)
-	Name() string
-	Output() io.Writer
-	Setenv(key, value string)
-	Skip(args ...any)
-	Skipf(format string, args ...any)
-	SkipNow()
-	Skipped() bool
-	TempDir() string
-}
-
-var _ TestingTB = testing.TB(nil)
+// Functions in this package use this type instead of [testing.TB] to allow
+// mocks of [testing.TB] to be substituted in tests for this package.
+type TestingTB = testcapture.TestingTB
diff --git a/assert/errequal_test.go b/assert/errequal_test.go
index b97342a..2cefeab 100644
--- a/assert/errequal_test.go
+++ b/assert/errequal_test.go
@@ -11,7 +11,6 @@ import (
 	"testing"
 
 	"go.xyrillian.de/gg/assert"
-	"go.xyrillian.de/gg/testcapture"
 )
 
 func TestErrEqual(t *testing.T) {
@@ -67,13 +66,10 @@ func TestErrEqual(t *testing.T) {
 	}, `expected an error matching /foo/, but got no error`)
 
 	// test matching against unexpected type
-	result := testcapture.Capture(t.Context(), t.Name(), func(t assert.TestingTB) {
+	result := assert.PanicsWith[string](t, func() {
 		assert.ErrEqual(t, errors.New("42"), 42)
 	})
-	assert.Equal(t, result, testcapture.Result{
-		Outcome: testcapture.OutcomePanicked,
-		Panic:   "cannot handle `expected` of type int",
-	})
+	assert.Equal(t, result, "cannot handle `expected` of type int")
 
 	// an earlier version had a bug because this call caused reflect.Value.IsNil() to be called on a value of kind Struct
 	expectErrors(t, func(t assert.TestingTB) {
diff --git a/assert/panic.go b/assert/panic.go
new file mode 100644
index 0000000..e19b815
--- /dev/null
+++ b/assert/panic.go
@@ -0,0 +1,32 @@
+// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
+// SPDX-License-Identifier: Apache-2.0
+
+package assert
+
+import (
+	"go.xyrillian.de/gg/testcapture"
+)
+
+// Panics runs the provided action and fails the test if it does not panic.
+// On success, the error value passed to the call of panic is returned.
+func Panics(t TestingTB, action func()) any {
+	return PanicsWith[any](t, action)
+}
+
+// PanicsWith is like Panics(), but also checks if the recovered error value
+// is of type T, failing the test if the type assertion fails.
+func PanicsWith[T any](t TestingTB, action func()) T {
+	t.Helper()
+	result := testcapture.Capture(t.Context(), t.Name(), func(_ TestingTB) {
+		action()
+	})
+	if result.Outcome != testcapture.OutcomePanicked {
+		t.Fatal("did not panic")
+	}
+	value, ok := result.Panic.(T)
+	if !ok {
+		var zero T
+		t.Fatalf("panicked with incorrect type: expected %T, but got %T: %#v", zero, result.Panic, result.Panic)
+	}
+	return value
+}
diff --git a/assert/panic_test.go b/assert/panic_test.go
new file mode 100644
index 0000000..a3d6877
--- /dev/null
+++ b/assert/panic_test.go
@@ -0,0 +1,35 @@
+// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
+// SPDX-License-Identifier: Apache-2.0
+
+package assert_test
+
+import (
+	"testing"
+
+	"go.xyrillian.de/gg/assert"
+	"go.xyrillian.de/gg/testcapture"
+)
+
+func TestPanics(t *testing.T) {
+	//only testing error cases here, coverage of the happy path is provided by
+	//usage of assert.Panics() in actual tests of other packages
+	tc := testcapture.Capture(t.Context(), t.Name(), func(t assert.TestingTB) {
+		assert.Panics(t, func() {
+			// no panic
+		})
+	})
+	assert.Equal(t, tc.Outcome, testcapture.OutcomeFailed)
+	assert.Equal(t, tc.Messages, []testcapture.Message{
+		testcapture.Log("did not panic"),
+	})
+
+	tc = testcapture.Capture(t.Context(), t.Name(), func(t assert.TestingTB) {
+		assert.PanicsWith[string](t, func() {
+			panic(42)
+		})
+	})
+	assert.Equal(t, tc.Outcome, testcapture.OutcomeFailed)
+	assert.Equal(t, tc.Messages, []testcapture.Message{
+		testcapture.Log("panicked with incorrect type: expected string, but got int: 42"),
+	})
+}