feat: added automatic snapshot testing

go.mod

@@ -11,6 +11,7 @@ require (
 )
 
 require (
+	github.com/bradleyjkemp/cupaloy v2.3.0+incompatible // indirect
 	github.com/kr/text v0.2.0 // indirect
 	golang.org/x/mod v0.4.2 // indirect
 	golang.org/x/sys v0.1.0 // indirect

go.sum

@@ -4,6 +4,8 @@ github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuy
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
 github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
+github.com/bradleyjkemp/cupaloy v2.3.0+incompatible h1:UafIjBvWQmS9i/xRg+CamMrnLTKNzo+bdmT/oH34c2Y=
+github.com/bradleyjkemp/cupaloy v2.3.0+incompatible/go.mod h1:Au1Xw1sgaJ5iSFktEhYsS0dbQiS1B0/XMXl+42y9Ilk=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=

snapshot_test.go

@@ -0,0 +1,133 @@
+package minimock_test
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"os/exec"
+	"testing"
+	"time"
+
+	"github.com/bradleyjkemp/cupaloy"
+)
+
+func mustRunMinimockWithParams(
+	t *testing.T,
+	interfacePattern string,
+	outputFile string,
+) {
+	t.Helper()
+
+	var outBuffer bytes.Buffer
+
+	timeoutContext, cancel := context.WithTimeout(context.Background(), time.Second*10)
+	defer cancel()
+
+	cmd := exec.CommandContext(timeoutContext, "go", "run", "cmd/minimock/minimock.go", "-o", outputFile, "-i", interfacePattern)
+	cmd.Stdout = &outBuffer
+	cmd.Stderr = &outBuffer
+
+	t.Log(cmd.String())
+
+	if err := cmd.Run(); err != nil {
+		t.Log(outBuffer.String())
+		t.Fail()
+	}
+}
+
+func mustReadFile(
+	t *testing.T,
+	filename string,
+) []byte {
+	t.Helper()
+
+	contents, err := os.ReadFile(filename)
+	if err != nil {
+		t.Errorf("failed to read the file: %v", err)
+		t.Fail()
+	}
+
+	return contents
+}
+
+func TestSnapshot(t *testing.T) {
+	snapshotter := cupaloy.New(
+		cupaloy.SnapshotSubdirectory("snapshots"),
+		cupaloy.SnapshotFileExtension(".go"),
+	)
+
+	type testCase struct {
+		name               string
+		outputFile         string
+		inputInterface     string
+		expectedOutputFile string
+	}
+
+	testCases := []testCase{
+		{
+			name:               "package reference",
+			outputFile:         "./tests",
+			inputInterface:     "github.com/gojuno/minimock/v3.Tester",
+			expectedOutputFile: "tests/tester_mock_test.go",
+		},
+		{
+			name:               "relative reference",
+			inputInterface:     "./tests.Formatter",
+			outputFile:         "./tests/formatter_mock.go",
+			expectedOutputFile: "./tests/formatter_mock.go",
+		},
+		{
+			name:               "generics with any used as param and return type",
+			inputInterface:     "./tests.genericInout",
+			outputFile:         "./tests/generic_inout.go",
+			expectedOutputFile: "./tests/generic_inout.go",
+		},
+		{
+			name:               "generics with any used as return type",
+			inputInterface:     "./tests.genericOut",
+			outputFile:         "./tests/generic_out.go",
+			expectedOutputFile: "./tests/generic_out.go",
+		},
+		{
+			name:               "generics with any used as param type",
+			inputInterface:     "./tests.genericIn",
+			outputFile:         "./tests/generic_in.go",
+			expectedOutputFile: "./tests/generic_in.go",
+		},
+		{
+			name:               "generics with specific type used as a generic constraint",
+			inputInterface:     "./tests.genericSpecific",
+			outputFile:         "./tests/generic_specific.go",
+			expectedOutputFile: "./tests/generic_specific.go",
+		},
+		{
+			name:               "generics with simple union used as a generic constraint",
+			inputInterface:     "./tests.genericSimpleUnion",
+			outputFile:         "./tests/generic_simple_union.go",
+			expectedOutputFile: "./tests/generic_simple_union.go",
+		},
+		{
+			name:               "generics with complex union used as a generic constraint",
+			inputInterface:     "./tests.genericComplexUnion",
+			outputFile:         "./tests/generic_complex_union.go",
+			expectedOutputFile: "./tests/generic_complex_union.go",
+		},
+		{
+			name:               "generics with complex inline union used as a generic constraint",
+			inputInterface:     "./tests.genericInlineUnion",
+			outputFile:         "./tests/generic_inline_union.go",
+			expectedOutputFile: "./tests/generic_inline_union.go",
+		},
+	}
+
+	for _, testCase := range testCases {
+		testCase := testCase
+
+		t.Run(testCase.name, func(t *testing.T) {
+			t.Parallel()
+
+			mustRunMinimockWithParams(t, testCase.inputInterface, testCase.outputFile)
+			snapshotter.SnapshotT(t, mustReadFile(t, testCase.expectedOutputFile))
+		})
+	}
+}