test: add unit tests for resolveBuilder in cmd/ci

cmd/ci/config_test.go

@@ -0,0 +1,47 @@
+package ci
+
+import (
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+// TestResolveBuilder covers the branching logic that selects the correct
+// build strategy for each runtime × local/remote combination.
+func TestResolveBuilder(t *testing.T) {
+	tests := []struct {
+		name    string
+		runtime string
+		remote  bool
+		want    string
+		wantErr bool
+	}{
+		{name: "go local", runtime: "go", remote: false, want: "host"},
+		{name: "go remote", runtime: "go", remote: true, want: "pack"},
+		{name: "node local", runtime: "node", remote: false, want: "pack"},
+		{name: "node remote", runtime: "node", remote: true, want: "pack"},
+		{name: "typescript local", runtime: "typescript", remote: false, want: "pack"},
+		{name: "typescript remote", runtime: "typescript", remote: true, want: "pack"},
+		{name: "rust local", runtime: "rust", remote: false, want: "pack"},
+		{name: "rust remote", runtime: "rust", remote: true, want: "pack"},
+		{name: "quarkus local", runtime: "quarkus", remote: false, want: "pack"},
+		{name: "quarkus remote", runtime: "quarkus", remote: true, want: "pack"},
+		{name: "springboot local", runtime: "springboot", remote: false, want: "pack"},
+		{name: "springboot remote", runtime: "springboot", remote: true, want: "pack"},
+		{name: "python local", runtime: "python", remote: false, want: "host"},
+		{name: "python remote", runtime: "python", remote: true, want: "s2i"},
+		{name: "unknown runtime", runtime: "fortran", remote: false, wantErr: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := resolveBuilder(tc.runtime, tc.remote)
+			if tc.wantErr {
+				assert.Assert(t, err != nil, "expected an error for runtime %q", tc.runtime)
+				return
+			}
+			assert.NilError(t, err)
+			assert.Equal(t, got, tc.want)
+		})
+	}
+}