From 33489d6344c05e14aaea8faf33a2b5b73c886215 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Sat, 14 Jan 2023 19:32:36 +0100
Subject: [PATCH] testing: implement t.Setenv

This method has been added in Go 1.17 and is used in archive/zip
starting with Go 1.20. Therefore, this method is now needed in Go 1.20.

I've left out the parts that disable parallel execution of tests,
because we don't do that in TinyGo.

See:
* https://github.com/golang/go/issues/41260
* https://go-review.googlesource.com/c/go/+/260577
---
 src/testing/testing.go      | 22 ++++++++++++++
 src/testing/testing_test.go | 57 +++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/src/testing/testing.go b/src/testing/testing.go
index c3d4b4ba..9c76f097 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -117,6 +117,7 @@ type TB interface {
 	Log(args ...interface{})
 	Logf(format string, args ...interface{})
 	Name() string
+	Setenv(key, value string)
 	Skip(args ...interface{})
 	SkipNow()
 	Skipf(format string, args ...interface{})
@@ -330,6 +331,27 @@ func (c *common) TempDir() string {
 	return dir
 }
 
+// Setenv calls os.Setenv(key, value) and uses Cleanup to
+// restore the environment variable to its original value
+// after the test.
+func (c *common) Setenv(key, value string) {
+	prevValue, ok := os.LookupEnv(key)
+
+	if err := os.Setenv(key, value); err != nil {
+		c.Fatalf("cannot set environment variable: %v", err)
+	}
+
+	if ok {
+		c.Cleanup(func() {
+			os.Setenv(key, prevValue)
+		})
+	} else {
+		c.Cleanup(func() {
+			os.Unsetenv(key)
+		})
+	}
+}
+
 // runCleanup is called at the end of the test.
 func (c *common) runCleanup() {
 	for {
diff --git a/src/testing/testing_test.go b/src/testing/testing_test.go
index b0b5ff06..8a258653 100644
--- a/src/testing/testing_test.go
+++ b/src/testing/testing_test.go
@@ -138,3 +138,60 @@ func testTempDir(t *testing.T) {
 		t.Errorf("unexpected files in TempDir")
 	}
 }
+
+func TestSetenv(t *testing.T) {
+	tests := []struct {
+		name               string
+		key                string
+		initialValueExists bool
+		initialValue       string
+		newValue           string
+	}{
+		{
+			name:               "initial value exists",
+			key:                "GO_TEST_KEY_1",
+			initialValueExists: true,
+			initialValue:       "111",
+			newValue:           "222",
+		},
+		{
+			name:               "initial value exists but empty",
+			key:                "GO_TEST_KEY_2",
+			initialValueExists: true,
+			initialValue:       "",
+			newValue:           "222",
+		},
+		{
+			name:               "initial value is not exists",
+			key:                "GO_TEST_KEY_3",
+			initialValueExists: false,
+			initialValue:       "",
+			newValue:           "222",
+		},
+	}
+
+	for _, test := range tests {
+		if test.initialValueExists {
+			if err := os.Setenv(test.key, test.initialValue); err != nil {
+				t.Fatalf("unable to set env: got %v", err)
+			}
+		} else {
+			os.Unsetenv(test.key)
+		}
+
+		t.Run(test.name, func(t *testing.T) {
+			t.Setenv(test.key, test.newValue)
+			if os.Getenv(test.key) != test.newValue {
+				t.Fatalf("unexpected value after t.Setenv: got %s, want %s", os.Getenv(test.key), test.newValue)
+			}
+		})
+
+		got, exists := os.LookupEnv(test.key)
+		if got != test.initialValue {
+			t.Fatalf("unexpected value after t.Setenv cleanup: got %s, want %s", got, test.initialValue)
+		}
+		if exists != test.initialValueExists {
+			t.Fatalf("unexpected value after t.Setenv cleanup: got %t, want %t", exists, test.initialValueExists)
+		}
+	}
+}