Add check.JSON and assert.JSON.

Author: rzajac

pkg/assert/json.go

@@ -0,0 +1,23 @@
+// SPDX-FileCopyrightText: (c) 2025 Rafal Zajac <rzajac@gmail.com>
+// SPDX-License-Identifier: MIT
+
+package assert
+
+import (
+	"github.com/ctx42/testing/pkg/check"
+	"github.com/ctx42/testing/pkg/tester"
+)
+
+// JSON asserts that two JSON strings are equivalent. Returns true if they are,
+// otherwise marks the test as failed, writes error message to test log and
+// returns false.
+//
+//	assert.JSON(t, `{"hello": "world"}`, `{"foo": "bar"}`)
+func JSON(t tester.T, want, have string, opts ...check.Option) bool {
+	t.Helper()
+	if e := check.JSON(want, have, opts...); e != nil {
+		t.Error(e)
+		return false
+	}
+	return true
+}

pkg/assert/json_test.go

@@ -0,0 +1,63 @@
+// SPDX-FileCopyrightText: (c) 2025 Rafal Zajac <rzajac@gmail.com>
+// SPDX-License-Identifier: MIT
+
+package assert
+
+import (
+	"testing"
+
+	"github.com/ctx42/testing/internal/affirm"
+	"github.com/ctx42/testing/pkg/check"
+	"github.com/ctx42/testing/pkg/tester"
+)
+
+func Test_JSON(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		// --- Given ---
+		tspy := tester.New(t).Close()
+
+		want := ` {"hello": "world"} `
+		have := " { \"hello\"\t:\n\n \"world\"\n\n\t}    "
+
+		// --- When ---
+		got := JSON(tspy, want, have)
+
+		// --- Then ---
+		affirm.True(t, got)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		// --- Given ---
+		tspy := tester.New(t)
+		tspy.ExpectError()
+		tspy.IgnoreLogs()
+		tspy.Close()
+
+		want := ` {"hello": "world"} `
+		have := " { \"hello\"\t:\n\n \"ms\"\n\n\t}    "
+
+		// --- When ---
+		got := JSON(tspy, want, have)
+
+		// --- Then ---
+		affirm.False(t, got)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		// --- Given ---
+		tspy := tester.New(t)
+		tspy.ExpectError()
+		tspy.ExpectLogContain("  trail: type.field\n")
+		tspy.Close()
+
+		want := ` {"hello": "world"} `
+		have := " { \"hello\"\t:\n\n \"ms\"\n\n\t}    "
+		opt := check.WithTrail("type.field")
+
+		// --- When ---
+		got := JSON(tspy, want, have, opt)
+
+		// --- Then ---
+		affirm.False(t, got)
+	})
+}

pkg/check/json.go

@@ -0,0 +1,45 @@
+// SPDX-FileCopyrightText: (c) 2025 Rafal Zajac <rzajac@gmail.com>
+// SPDX-License-Identifier: MIT
+
+package check
+
+import (
+	"encoding/json"
+
+	"github.com/ctx42/testing/pkg/notice"
+)
+
+// JSON checks that two JSON strings are equivalent. Returns nil if they are,
+// otherwise it returns an error with a message indicating the expected and
+// actual values.
+//
+// Example:
+//
+//	check.JSON(`{"hello": "world"}`, `{"foo": "bar"}`)
+func JSON(want, have string, opts ...Option) error {
+	var wantItf, haveItf any
+
+	ops := DefaultOptions(opts...)
+	if err := json.Unmarshal([]byte(want), &wantItf); err != nil {
+		return notice.New("did not expect unmarshalling error").
+			Trail(ops.Trail).
+			Append("argument", "want").
+			Append("error", "%s", err)
+	}
+	if err := json.Unmarshal([]byte(have), &haveItf); err != nil {
+		return notice.New("did not expect unmarshalling error").
+			Trail(ops.Trail).
+			Append("argument", "have").
+			Append("error", "%s", err)
+	}
+
+	if err := Equal(wantItf, haveItf, WithOptions(ops)); err != nil {
+		w, _ := json.Marshal(wantItf) // nolint:errchkjson
+		h, _ := json.Marshal(haveItf) // nolint:errchkjson
+		return notice.New("expected JSON strings to be equal").
+			Trail(ops.Trail).
+			Want("%v", string(w)).
+			Have("%v", string(h))
+	}
+	return nil
+}

pkg/check/json_test.go

@@ -0,0 +1,80 @@
+// SPDX-FileCopyrightText: (c) 2025 Rafal Zajac <rzajac@gmail.com>
+// SPDX-License-Identifier: MIT
+
+package check
+
+import (
+	"testing"
+
+	"github.com/ctx42/testing/internal/affirm"
+)
+
+func Test_JSON(t *testing.T) {
+	t.Run("equal", func(t *testing.T) {
+		// --- Given ---
+		want := ` {"hello": "world"} `
+		have := " { \"hello\"\t:\n\n \"world\"\n\n\t}    "
+
+		// --- When ---
+		err := JSON(want, have)
+
+		// --- Then ---
+		affirm.Nil(t, err)
+	})
+
+	t.Run("not equal", func(t *testing.T) {
+		// --- Given ---
+		want := ` {"hello": "world"} `
+		have := " { \"hello\"\t:\n\n \"ms\"\n\n\t}    "
+		opt := WithTrail("type.field")
+
+		// --- When ---
+		err := JSON(want, have, opt)
+
+		// --- Then ---
+		affirm.NotNil(t, err)
+		wMsg := "expected JSON strings to be equal:\n" +
+			"  trail: type.field\n" +
+			"   want: {\"hello\":\"world\"}\n" +
+			"   have: {\"hello\":\"ms\"}"
+		affirm.Equal(t, wMsg, err.Error())
+	})
+
+	t.Run("invalid want JSON", func(t *testing.T) {
+		// --- Given ---
+		want := `{!!!}`
+		have := `{"hello": "world"}`
+		opt := WithTrail("type.field")
+
+		// --- When ---
+		err := JSON(want, have, opt)
+
+		// --- Then ---
+		affirm.NotNil(t, err)
+		wMsg := "did not expect unmarshalling error:\n" +
+			"     trail: type.field\n" +
+			"  argument: want\n" +
+			"     error: invalid character '!' looking for beginning of " +
+			"object key string"
+		affirm.Equal(t, wMsg, err.Error())
+	})
+
+	t.Run("invalid have JSON", func(t *testing.T) {
+		// --- Given ---
+		want := `{"hello": "world"}`
+		have := `{!!!}`
+		opt := WithTrail("type.field")
+
+		// --- When ---
+		err := JSON(want, have, opt)
+
+		// --- Then ---
+		affirm.NotNil(t, err)
+		wMsg := "did not expect unmarshalling error:\n" +
+			"     trail: type.field\n" +
+			"  argument: have\n" +
+			"     error: invalid character '!' looking for beginning of " +
+			"object key string"
+		affirm.Equal(t, wMsg, err.Error())
+	})
+}