adding test cases, a Makefile so that the tests can be run recursivel…

…y within subdirectories, README update

.vscode/settings.json

@@ -1,10 +1,14 @@
 {
+  "[go]": {
+    "editor.tabSize": 4,
+    "editor.insertSpaces": true
+  },
   "[json]": {
     "editor.tabSize": 2,
     "editor.insertSpaces": true
   },
-  "[go]": {
+  "[makefile]": {
     "editor.tabSize": 4,
-    "editor.insertSpaces": true
+    "editor.insertSpaces": false
   }
 }

Makefile

@@ -0,0 +1,3 @@
+test:
+	@echo "Running tests recursively..."
+	go test ./...

README.md

@@ -37,6 +37,14 @@ A screenshot of the results:
 
 ![results](screenshots/results.png)
 
+## Testing
+
+Run all tests (including tests in subdirectories):
+
+```bash
+make test
+```
+
 ## Acknowledgements
 
 A big thanks to [u/Disciplined2021](https://www.reddit.com/user/Disciplined2021/) for the initial work compiling the list of duels and results.

utils/helpers.go

@@ -7,7 +7,7 @@ import (
 	"os"
 )
 
-// calculateExpectedScore calculates the expected score for a participant
+// calculates the expected score for a duelist
 func CalculateExpectedScore(ratingA, ratingB float64) float64 {
 	return 1 / (1 + math.Pow(10, (ratingB-ratingA)/400))
 }

utils/helpers_test.go

@@ -0,0 +1,55 @@
+package utils
+
+import (
+    "math"
+    "testing"
+)
+
+func TestGetUniqueNames(t *testing.T) {
+    duels := []Duel{
+        {Duelist: "Alice", Versus: "Bob", MultiDuelists: []string{"Charlie", "David"}},
+        {Duelist: "Bob", Versus: "Alice", MultiDuelists: []string{"Charlie", "David"}},
+        {Duelist: "Charlie", Versus: "David", MultiDuelists: []string{"Alice", "Bob"}},
+    }
+    expected := []string{"Alice", "Bob", "Charlie", "David"}
+    names := GetUniqueNames(duels)
+    if len(names) != len(expected) {
+        t.Errorf("got %v; expected %v", names, expected)
+    }
+    for i, name := range names {
+        if name != expected[i] {
+            t.Errorf("got %v; expected %v", name, expected[i])
+        }
+    }
+}
+
+func TestUpdateRatings(t *testing.T) {
+    duelistNames := []string{"Alice", "Bob", "Charlie", "David"}
+    duelists := make(map[string]*Duelist)
+	for _, name := range duelistNames {
+		duelists[name] = &Duelist{Name: name, Rating: 1000}
+	}
+
+    duels := []Duel{
+        {Duelist: "Alice", Versus: "Bob", Winner: "Alice"},
+        {Duelist: "Charlie", Versus: "David", Winner: "David"},
+        {Duelist: "Bob", Versus: "Alice", Winner: "Bob"},
+    }
+
+    for _, duel := range duels {
+        UpdateRatings(duelists, duel)
+    }
+
+    expected := map[string]float64{
+        "Alice": 998.53,
+        "Bob": 1001.47,
+        "Charlie": 984,
+        "David": 1016,
+    }
+
+    for name, rating := range expected {
+        if (math.Round(duelists[name].Rating * 100) / 100) != rating {
+            t.Errorf("got %v; expected %v", duelists[name].Rating, rating)
+        }
+    }
+}