refactor: improve code structure and add tests

any.go

@@ -0,0 +1,26 @@
+package gomockctx
+
+import (
+	"context"
+
+	"github.com/golang/mock/gomock"
+)
+
+// Any returns a gomock.Matcher which matches any context.Context object.
+func Any() gomock.Matcher {
+	return &anyMatcher{}
+}
+
+type anyMatcher struct{}
+
+var _ gomock.Matcher = &anyMatcher{}
+
+func (cm *anyMatcher) Matches(x interface{}) bool {
+	_, ok := x.(context.Context)
+
+	return ok
+}
+
+func (cm *anyMatcher) String() string {
+	return "is a context.Context"
+}

any_test.go

@@ -0,0 +1,155 @@
+package gomockctx
+
+import (
+	"context"
+	"testing"
+
+	"github.com/golang/mock/gomock"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAny(t *testing.T) {
+	tests := []struct {
+		name string
+		x    interface{}
+		want bool
+	}{
+		{
+			name: "nil",
+			x:    nil,
+			want: false,
+		},
+		{
+			name: "empty string",
+			x:    "",
+			want: false,
+		},
+		{
+			name: "string",
+			x:    "foo bar",
+			want: false,
+		},
+		{
+			name: "int",
+			x:    42,
+			want: false,
+		},
+		{
+			name: "int8",
+			x:    int8(64),
+			want: false,
+		},
+		{
+			name: "int16",
+			x:    int16(1024),
+			want: false,
+		},
+		{
+			name: "int32",
+			x:    int32(1123456789),
+			want: false,
+		},
+		{
+			name: "int64",
+			x:    int64(16123456789),
+			want: false,
+		},
+		{
+			name: "uint",
+			x:    uint(616),
+			want: false,
+		},
+		{
+			name: "uint8",
+			x:    uint8(64),
+			want: false,
+		},
+		{
+			name: "uint16",
+			x:    uint16(1024),
+			want: false,
+		},
+		{
+			name: "uint32",
+			x:    uint32(1123456789),
+			want: false,
+		},
+		{
+			name: "uint64",
+			x:    uint64(16123456789),
+			want: false,
+		},
+		{
+			name: "byte",
+			x:    byte('A'),
+			want: false,
+		},
+		{
+			name: "rune",
+			x:    rune('A'),
+			want: false,
+		},
+		{
+			name: "float32",
+			x:    float32(6.16),
+			want: false,
+		},
+		{
+			name: "float64",
+			x:    float64(6.16),
+			want: false,
+		},
+		{
+			name: "bool",
+			x:    true,
+			want: false,
+		},
+		{
+			name: "slice",
+			x:    []string{"foo", "bar"},
+			want: false,
+		},
+		{
+			name: "array",
+			x:    [2]string{"foo", "bar"},
+			want: false,
+		},
+		{
+			name: "channel",
+			x:    make(chan bool),
+			want: false,
+		},
+		{
+			name: "func",
+			x:    func() {},
+			want: false,
+		},
+		{
+			name: "context.Background()",
+			x:    context.Background(),
+			want: true,
+		},
+		{
+			name: "context.TODO()",
+			x:    context.TODO(),
+			want: true,
+		},
+		{
+			name: "custom context",
+			x:    context.WithValue(context.Background(), ctxKey, "foo"),
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			m := Any()
+			require.Implements(t, (*gomock.Matcher)(nil), m)
+
+			got := m.Matches(tt.x)
+
+			assert.Equal(t, tt.want, got)
+			assert.Equal(t, "is a context.Context", m.String())
+		})
+	}
+}

gomockctx.go

@@ -4,8 +4,6 @@ package gomockctx
 
 import (
 	"context"
-	"fmt"
-	"reflect"
 
 	"github.com/golang/mock/gomock"
 )
@@ -15,76 +13,10 @@ type (
 	contextValue string
 )
 
-var ctxKey contextKey = "gomockctx context ID"
-
-// New returns a context as a child of the given parent, and with a randomized
-// gomockctx ID value set, making it a gomockctx context. This can then be used
-// with Is to get a gomock Matcher which returns true for the context from New,
-// or any child contexts of it.
-//
-// If crypto/rand returns an error, this will panic trying to generate the
-// gomockctx ID. In practise though, crypto/rand should never return a error.
-func New(parent context.Context) context.Context {
-	return context.WithValue(parent, ctxKey, newCtxID())
-}
-
-// Is accepts a context with a gomockctx ID value (as returned from New), and
-// returns a gomock.Matcher which returns true for the given context, of any
-// child contexts of it.
-//
-// If ctx was not returned from New, the resulting matcher will ALWAYS return
-// false.
-func Is(ctx context.Context) gomock.Matcher {
-	return WithValue(ctxKey, value(ctx))
-}
-
-// ID returns the gomockctx ID value in the given context, or a empty string if
-// the context does not have a gomockctx ID value.
-func ID(ctx context.Context) string {
-	if ctx == nil {
-		return ""
-	}
-
-	return string(value(ctx))
-}
-
-// Any returns a gomock.Matcher which matches any context.Context object.
-func Any() gomock.Matcher {
-	return gomock.AssignableToTypeOf(
-		reflect.TypeOf((*context.Context)(nil)).Elem(),
-	)
-}
-
-// WithValue returns a gomock.Matcher which matches any context that has the
-// specified key and value.
-func WithValue(key interface{}, value interface{}) gomock.Matcher {
-	return &contextMatcher{
-		key:   key,
-		value: value,
-	}
-}
-
-type contextMatcher struct {
-	key   interface{}
-	value interface{}
-}
-
-var _ gomock.Matcher = &contextMatcher{}
-
-func (cm *contextMatcher) Matches(x interface{}) bool {
-	if ctx, ok := x.(context.Context); ok {
-		return reflect.DeepEqual(cm.value, ctx.Value(cm.key))
-	}
-
-	return false
-}
-
-func (cm *contextMatcher) String() string {
-	return fmt.Sprintf(`context with "%+v" = "%+v"`, cm.key, cm.value)
-}
+var ctxKey contextKey = "gomockctx ID"
 
 func newCtxID() contextValue {
-	id, err := randString(64)
+	id, err := randString(32)
 	if err != nil {
 		panic(err)
 	}
@@ -92,7 +24,7 @@ func newCtxID() contextValue {
 	return contextValue(id)
 }
 
-func value(ctx context.Context) contextValue {
+func getValue(ctx context.Context) contextValue {
 	var value contextValue
 	if ctx == nil {
 		return value
@@ -105,3 +37,34 @@ func value(ctx context.Context) contextValue {
 
 	return value
 }
+
+// New returns a context as a child of the given parent, which includes a
+// randomized gomockctx ID value set, which makes it a gomockctx context. This
+// can then be used with Is to get a gomock Matcher which returns true for the
+// context from New, or any child contexts of it.
+//
+// If crypto/rand returns an error, this will panic trying to generate the
+// gomockctx ID. In practice though, crypto/rand should never return a error.
+func New(parent context.Context) context.Context {
+	return context.WithValue(parent, ctxKey, newCtxID())
+}
+
+// Is accepts a context with a gomockctx ID value (as returned from New), and
+// returns a gomock.Matcher which returns true for the given context, of any
+// child contexts of it.
+//
+// If ctx was not returned from New, the resulting matcher will ALWAYS return
+// false.
+func Is(ctx context.Context) gomock.Matcher {
+	return WithValue(ctxKey, getValue(ctx))
+}
+
+// ID returns the gomockctx ID value in the given context, or a empty string if
+// the context does not have a gomockctx ID value.
+func ID(ctx context.Context) string {
+	if ctx == nil {
+		return ""
+	}
+
+	return string(getValue(ctx))
+}

gomockctx_test.go

@@ -2,11 +2,113 @@ package gomockctx
 
 import (
 	"context"
+	"regexp"
 	"testing"
 
+	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
+func TestNew(t *testing.T) {
+	type key struct{}
+	k := key{}
+	ctxIDRegexp := regexp.MustCompile(`^[A-Za-z0-9]+$`)
+	parent := context.WithValue(context.Background(), k, "the parent")
+
+	ids := map[contextValue]struct{}{}
+	limit := 1000
+
+	for i := 0; i < limit; i++ {
+		ctx := New(parent)
+		require.Equal(t, "the parent", ctx.Value(k))
+
+		v := ctx.Value(ctxKey)
+		require.IsType(t, contextValue(""), v)
+		require.Len(t, v, 32)
+		require.Regexp(t, ctxIDRegexp, v)
+		cv, _ := v.(contextValue)
+		ids[cv] = struct{}{}
+	}
+
+	assert.Len(t, ids, limit)
+}
+
+func TestIs(t *testing.T) {
+	type strKey string
+
+	type args struct {
+		ctx context.Context
+	}
+	tests := []struct {
+		name string
+		args args
+		want *valueMatcher
+	}{
+		{
+			name: "nil",
+			args: args{
+				ctx: nil,
+			},
+			want: &valueMatcher{
+				key:   ctxKey,
+				value: contextValue(""),
+			},
+		},
+		{
+			name: "context without gomockctx ID",
+			args: args{
+				ctx: context.Background(),
+			},
+			want: &valueMatcher{
+				key:   ctxKey,
+				value: contextValue(""),
+			},
+		},
+		{
+			name: "context with gomockctx ID",
+			args: args{
+				ctx: context.WithValue(
+					context.Background(),
+					ctxKey,
+					contextValue("z9KZVcfmA4sWJX0yuIIESVcEARlwiAT2"),
+				),
+			},
+			want: &valueMatcher{
+				key:   ctxKey,
+				value: contextValue("z9KZVcfmA4sWJX0yuIIESVcEARlwiAT2"),
+			},
+		},
+		{
+			name: "child context of context with gomockctx ID",
+			args: args{
+				ctx: context.WithValue(
+					context.WithValue(
+						context.Background(),
+						ctxKey,
+						contextValue("hWEKf4Gtj15iLx4R7IFlHc5ooj5tU4UW"),
+					),
+					strKey("foo"),
+					"bar",
+				),
+			},
+			want: &valueMatcher{
+				key:   ctxKey,
+				value: contextValue("hWEKf4Gtj15iLx4R7IFlHc5ooj5tU4UW"),
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := Is(tt.args.ctx)
+
+			assert.Implements(t, (*gomock.Matcher)(nil), got)
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
 func TestID(t *testing.T) {
 	tests := []struct {
 		name string

with_value.go

@@ -0,0 +1,37 @@
+package gomockctx
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+
+	"github.com/golang/mock/gomock"
+)
+
+// WithValue returns a gomock.Matcher which matches any context that has the
+// specified key and value.
+func WithValue(key interface{}, value interface{}) gomock.Matcher {
+	return &valueMatcher{
+		key:   key,
+		value: value,
+	}
+}
+
+type valueMatcher struct {
+	key   interface{}
+	value interface{}
+}
+
+var _ gomock.Matcher = &valueMatcher{}
+
+func (cm *valueMatcher) Matches(x interface{}) bool {
+	if ctx, ok := x.(context.Context); ok {
+		return reflect.DeepEqual(cm.value, ctx.Value(cm.key))
+	}
+
+	return false
+}
+
+func (cm *valueMatcher) String() string {
+	return fmt.Sprintf(`context with "%+v" = "%+v"`, cm.key, cm.value)
+}

with_value_test.go

@@ -0,0 +1,468 @@
+package gomockctx
+
+import (
+	"context"
+	"testing"
+
+	"github.com/golang/mock/gomock"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWithValue(t *testing.T) {
+	type args struct {
+		key   interface{}
+		value interface{}
+	}
+	tests := []struct {
+		name string
+		args args
+		want *valueMatcher
+	}{
+		{
+			name: "nil",
+			args: args{
+				key:   nil,
+				value: nil,
+			},
+			want: &valueMatcher{
+				key:   nil,
+				value: nil,
+			},
+		},
+		{
+			name: "string",
+			args: args{
+				key:   "foo",
+				value: "bar",
+			},
+			want: &valueMatcher{
+				key:   "foo",
+				value: "bar",
+			},
+		},
+		{
+			name: "gomockctx ctxKey",
+			args: args{
+				key:   ctxKey,
+				value: "FrAcGnKKpVk1rB3AWC9S8Dnff04svNtN",
+			},
+			want: &valueMatcher{
+				key:   ctxKey,
+				value: "FrAcGnKKpVk1rB3AWC9S8Dnff04svNtN",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := WithValue(tt.args.key, tt.args.value)
+
+			assert.Implements(t, (*gomock.Matcher)(nil), got)
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func Test_valueMatcher_Matches(t *testing.T) {
+	ctx := context.Background()
+
+	type stringKey string
+	strKey := stringKey("strKey")
+	strKeyVal1 := "foo"
+	strKeyVal2 := "bar"
+	ctxWithStrKey := context.WithValue(ctx, strKey, strKeyVal1)
+
+	structKey := struct{}{}
+	structKeyVal1 := struct{ name string }{name: "foo"}
+	structKeyVal2 := struct{ name string }{name: "bar"}
+	ctxWithStructKey := context.WithValue(ctx, structKey, structKeyVal1)
+
+	ctxKeyVal1 := "XAzb0Cr7yLuLzO369vTodjxKL3GUpspE"
+	ctxKeyVal2 := "r11X0FOejbPamvLiWhAuGiSqXzdmGnIm"
+	ctxWithCtxKey := context.WithValue(ctx, ctxKey, ctxKeyVal1)
+
+	type fields struct {
+		key   interface{}
+		value interface{}
+	}
+	type args struct {
+		x interface{}
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   bool
+	}{
+		{
+			name: "nil",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: nil},
+			want: false,
+		},
+		{
+			name: "empty string",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: ""},
+			want: false,
+		},
+		{
+			name: "string",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: "hello world"},
+			want: false,
+		},
+		{
+			name: "int",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: int(616)},
+			want: false,
+		},
+		{
+			name: "int8",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: int8(64)},
+			want: false,
+		},
+		{
+			name: "int16",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: int16(1024)},
+			want: false,
+		},
+		{
+			name: "int32",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: int32(1123456789)},
+			want: false,
+		},
+		{
+			name: "int64",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: int64(16123456789)},
+			want: false,
+		},
+		{
+			name: "uint",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: uint(616)},
+			want: false,
+		},
+		{
+			name: "uint8",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: uint8(64)},
+			want: false,
+		},
+		{
+			name: "uint16",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: uint16(1024)},
+			want: false,
+		},
+		{
+			name: "uint32",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: uint32(1123456789)},
+			want: false,
+		},
+		{
+			name: "uint64",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: uint64(16123456789)},
+			want: false,
+		},
+		{
+			name: "byte",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: byte('A')},
+			want: false,
+		},
+		{
+			name: "rune",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: rune('A')},
+			want: false,
+		},
+		{
+			name: "float32",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: float32(6.16)},
+			want: false,
+		},
+		{
+			name: "float64",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: float64(6.16)},
+			want: false,
+		},
+		{
+			name: "bool",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: 616},
+			want: false,
+		},
+		{
+			name: "slice",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: []string{"foo", "bar"}},
+			want: false,
+		},
+		{
+			name: "array",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: [2]string{"foo", "bar"}},
+			want: false,
+		},
+		{
+			name: "channel",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: make(chan bool)},
+			want: false,
+		},
+		{
+			name: "func",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: func() {}},
+			want: false,
+		},
+		{
+			name: "context with strKey",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: ctxWithStrKey},
+			want: true,
+		},
+		{
+			name: "context with different strKey",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal2,
+			},
+			args: args{x: ctxWithStrKey},
+			want: false,
+		},
+		{
+			name: "context without strKey",
+			fields: fields{
+				key:   strKey,
+				value: strKeyVal1,
+			},
+			args: args{x: ctx},
+			want: false,
+		},
+		{
+			name: "context with structKey",
+			fields: fields{
+				key:   structKey,
+				value: structKeyVal1,
+			},
+			args: args{x: ctxWithStructKey},
+			want: true,
+		},
+		{
+			name: "context with different structKey",
+			fields: fields{
+				key:   structKey,
+				value: structKeyVal2,
+			},
+			args: args{x: ctxWithStructKey},
+			want: false,
+		},
+		{
+			name: "context without structKey",
+			fields: fields{
+				key:   structKey,
+				value: structKeyVal1,
+			},
+			args: args{x: ctx},
+			want: false,
+		},
+		{
+			name: "context with ctxKey",
+			fields: fields{
+				key:   ctxKey,
+				value: ctxKeyVal1,
+			},
+			args: args{x: ctxWithCtxKey},
+			want: true,
+		},
+		{
+			name: "context with different ctxKey",
+			fields: fields{
+				key:   ctxKey,
+				value: ctxKeyVal2,
+			},
+			args: args{x: ctxWithCtxKey},
+			want: false,
+		},
+		{
+			name: "context without ctxKey",
+			fields: fields{
+				key:   ctxKey,
+				value: ctxKeyVal1,
+			},
+			args: args{x: ctx},
+			want: false,
+		},
+		{
+			name: "context with ctxKey and empty value",
+			fields: fields{
+				key:   ctxKey,
+				value: contextValue(""),
+			},
+			args: args{x: ctxWithCtxKey},
+			want: false,
+		},
+		{
+			name: "context with different ctxKey and empty value",
+			fields: fields{
+				key:   ctxKey,
+				value: contextValue(""),
+			},
+			args: args{x: ctxWithCtxKey},
+			want: false,
+		},
+		{
+			name: "context without ctxKey and empty value",
+			fields: fields{
+				key:   ctxKey,
+				value: contextValue(""),
+			},
+			args: args{x: ctx},
+			want: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			vm := &valueMatcher{
+				key:   tt.fields.key,
+				value: tt.fields.value,
+			}
+
+			got := vm.Matches(tt.args.x)
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func Test_valueMatcher_String(t *testing.T) {
+	type stringKey string
+	type structKey struct{ name string }
+
+	type fields struct {
+		key   interface{}
+		value interface{}
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		want   string
+	}{
+		{
+			name: "stringKey",
+			fields: fields{
+				key:   stringKey("foo"),
+				value: "hello world",
+			},
+			want: `context with "foo" = "hello world"`,
+		},
+		{
+			name: "structKey",
+			fields: fields{
+				key:   structKey{name: "bar"},
+				value: "okay then",
+			},
+			want: `context with "{name:bar}" = "okay then"`,
+		},
+		{
+			name: "gomockctx ctxKey",
+			fields: fields{
+				key:   ctxKey,
+				value: "foobar",
+			},
+			want: `context with "gomockctx ID" = "foobar"`,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			vm := &valueMatcher{
+				key:   tt.fields.key,
+				value: tt.fields.value,
+			}
+
+			got := vm.String()
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}