Agree a toolchain by strict majority and name the nodes that sit out (ADR 0584, issue 1578)

One build node on another version stopped every build of the language. The agreed toolchain is now the strict majority's; a tie still waits and names the versions. Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL
2026-11-01 15:20:26 +01:00
parent cad8250aaa
commit a6c6d936d5
2 changed files with 86 additions and 40 deletions
@@ -55,36 +55,50 @@ func TestToolchainKeyAndValue(t *testing.T) {
 	}
 }

-// 1443/AC2
-func TestAgreedToolchain(t *testing.T) {
-	tc, none := AgreedToolchain([]NodeToolchain{tcEntry("ace", "go", "1.26.1", "3"), tcEntry("novox", "go", "1.26.1", "3")})
-	if tc != (Toolchain2{Language: "go", Version: "1.26.1", Recipe: "3"}) || none != "" {
-		t.Errorf("%+v %q", tc, none)
-	}
-}
-
-// 1443/AC3
-func TestAgreedToolchainNoReport(t *testing.T) {
-	tc, none := AgreedToolchain(nil)
-	if tc != (Toolchain2{}) || none != "toolchain not yet reported" {
-		t.Errorf("%+v %q", tc, none)
-	}
-}
-
-// 1443/AC4
-func TestAgreedToolchainDisagree(t *testing.T) {
-	a, b, c := tcEntry("ace", "go", "1.26.1", "3"), tcEntry("novox", "go", "1.26.2", "3"), tcEntry("g14", "go", "1.26.1", "4")
-	_, first := AgreedToolchain([]NodeToolchain{a, b, c})
-	_, second := AgreedToolchain([]NodeToolchain{c, b, a})
-	if first == "" || first != second {
-		t.Errorf("order changed the answer: %q vs %q", first, second)
-	}
-	for _, want := range []string{"builders disagree", "1.26.1", "1.26.2", "ace", "novox", "g14"} {
-		if !strings.Contains(first, want) {
-			t.Errorf("%q does not name %q", first, want)
+// 1443/AC2-4, ADR 0584: the agreed toolchain is the strict majority's; a minority node sits out; a tie waits.
+func TestToolchainAgreement(t *testing.T) {
+	e := tcEntry
+	for _, c := range []struct {
+		name    string
+		in      []NodeToolchain
+		version string
+		out     []SittingOut
+		wait    []string // "" wait means agreed
+	}{
+		{"all agree", []NodeToolchain{e("ace", "go", "1.26.1", "3"), e("novox", "go", "1.26.1", "3")}, "1.26.1", nil, nil},
+		{"three against one", []NodeToolchain{e("ace", "typescript", "26.12.1", "3"), e("g14", "typescript", "26.13.0", "3"), e("novox", "typescript", "26.13.0", "3"), e("shanks", "typescript", "26.13.0", "3")},
+			"26.13.0", []SittingOut{{"ace", "26.12.1", "3"}}, nil},
+		{"two against two", []NodeToolchain{e("ace", "go", "1.26.1", "3"), e("novox", "go", "1.26.2", "3"), e("g14", "go", "1.26.1", "3"), e("shanks", "go", "1.26.2", "3")},
+			"", nil, []string{"builders disagree", "1.26.1 recipe 3 on ace, g14", "1.26.2 recipe 3 on novox, shanks"}},
+		{"one node alone", []NodeToolchain{e("ace", "go", "1.26.1", "3")}, "1.26.1", nil, nil},
+		{"no report", nil, "", nil, []string{ToolchainNoReport}},
+	} {
+		a := ToolchainAgreement(c.in)
+		rev := make([]NodeToolchain, len(c.in))
+		for i, x := range c.in {
+			rev[len(c.in)-1-i] = x
+		}
+		if b := ToolchainAgreement(rev); b.Wait != a.Wait || b.Toolchain != a.Toolchain {
+			t.Errorf("%s: order changed the answer: %+v vs %+v", c.name, a, b)
+		}
+		if a.Toolchain.Version != c.version || len(a.SittingOut) != len(c.out) {
+			t.Errorf("%s: %+v", c.name, a)
+		}
+		for i := range c.out {
+			if a.SittingOut[i] != c.out[i] {
+				t.Errorf("%s: sitting out %+v, want %+v", c.name, a.SittingOut, c.out)
+			}
+		}
+		if (len(c.wait) == 0) != (a.Wait == "") {
+			t.Errorf("%s: wait %q", c.name, a.Wait)
+		}
+		for _, w := range c.wait {
+			if !strings.Contains(a.Wait, w) {
+				t.Errorf("%s: %q does not name %q", c.name, a.Wait, w)
+			}
+		}
+		if tc, none := AgreedToolchain(c.in); tc != a.Toolchain || none != a.Wait {
+			t.Errorf("%s: AgreedToolchain %+v %q", c.name, tc, none)
 		}
 	}
-	if tc, _ := AgreedToolchain([]NodeToolchain{a, b}); tc != (Toolchain2{}) {
-		t.Errorf("a disagreement gave %+v", tc)
-	}
 }