feat: New exercises (concurrency)

2 files changed, 77 insertions, 0 deletions

diff --git a/exercises/concurrent/concurrent1/main_test.go b/exercises/concurrent/concurrent1/main_test.go
new file mode 100644
index 0000000..3965113
--- /dev/null
+++ b/exercises/concurrent/concurrent1/main_test.go
@@ -0,0 +1,45 @@
+// concurrent1
+// Make the tests pass!
+
+// I AM NOT DONE
+package main_test
+
+import (
+	"bytes"
+	"fmt"
+	"sync"
+	"testing"
+)
+
+func TestPrinter(t *testing.T) {
+	var buf bytes.Buffer
+	print(&buf)
+
+	out := buf.String()
+
+	for i := 0; i < 3; i++ {
+		want := fmt.Sprintf("Hello from goroutine %d!", i)
+		if !bytes.Contains([]byte(out), []byte(want)) {
+			t.Errorf("Output did not contain expected string. Wanted: %q, Got: %q", want, out)
+		}
+	}
+}
+
+func print(buf *bytes.Buffer) {
+	var wg sync.WaitGroup
+	var mu sync.Mutex
+
+	goroutines := 3
+
+	for i := 0; i < goroutines; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			mu.Lock()
+			//fmt.Fprintf(buf, "Hello from goroutine %d!\n", i)
+			mu.Unlock()
+		}(i)
+	}
+
+	wg.Wait()
+}
diff --git a/exercises/concurrent/concurrent2/main_test.go b/exercises/concurrent/concurrent2/main_test.go
new file mode 100644
index 0000000..2233259
--- /dev/null
+++ b/exercises/concurrent/concurrent2/main_test.go
@@ -0,0 +1,32 @@
+// concurrent2
+// Make the tests pass!
+
+// I AM NOT DONE
+package main_test
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestCounter(t *testing.T) {
+	counter := updateCounter()
+	if counter != 100 {
+		t.Errorf("Counter should be 100, but got %d", counter)
+	}
+}
+
+func updateCounter() int {
+	var counter int
+	var wg sync.WaitGroup
+
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			counter++ // Many goroutines trying to update the counter? We need some protection here!
+		}()
+	}
+	wg.Wait()
+	return counter
+}