Add recompute recovery acceptance coverage

internal/cli/run_contract_test.go

@@ -60,6 +60,56 @@ func TestRunControlsRejectSyntaxWithoutAllocatingState(t *testing.T) {
 	}
 }
 
+func TestRecomputeStepCLIContract(t *testing.T) {
+	tests := []struct {
+		name       string
+		configure  func(*testing.T, stateTestRoots)
+		flags      []string
+		wantCode   int
+		wantOutput string
+		wantError  string
+	}{
+		{
+			name: "explicit step",
+			configure: func(t *testing.T, roots stateTestRoots) {
+				replaceStateTestConfigLine(t, roots.config, "    artifacts:\n      items:\n        extract: test/extract\n        merge: test/merge\n        normalize: test/normalize\n", "    steps:\n      - id: chosen\n        artifacts:\n          items:\n            extract: test/extract\n            merge: test/merge\n            normalize: test/normalize\n")
+			},
+			flags:      []string{"--resume", "--recompute-step", "chosen"},
+			wantCode:   0,
+			wantOutput: "outputs=1",
+		},
+		{name: "implicit default step", flags: []string{"--resume", "--recompute-step", "default"}, wantCode: 0, wantOutput: "outputs=1"},
+		{name: "repeated flag", flags: []string{"--resume", "--recompute-step", "default", "--recompute-step", "default"}, wantCode: 2, wantError: "specified only once"},
+		{name: "empty step", flags: []string{"--resume", "--recompute-step", ""}, wantCode: 2, wantError: "must not be empty"},
+		{name: "unknown step", flags: []string{"--resume", "--recompute-step", "missing"}, wantCode: 1, wantError: "unknown pipeline step"},
+		{name: "without resume", flags: []string{"--recompute-step", "default"}, wantCode: 2, wantError: "requires --resume"},
+		{
+			name: "checkpoint recording disabled",
+			configure: func(t *testing.T, roots stateTestRoots) {
+				replaceStateTestConfigLine(t, roots.config, "    enabled: true\n", "    enabled: false\n")
+			},
+			flags: []string{"--resume", "--recompute-step", "default"}, wantCode: 1, wantError: "cache.checkpoints.enabled",
+		},
+		{name: "with only", flags: []string{"--resume", "--recompute-step", "default", "--only", "items"}, wantCode: 2, wantError: "cannot be combined with --only"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			roots := newStateTestRoots(t)
+			if tt.configure != nil {
+				tt.configure(t, roots)
+			}
+			args := []string{"run", "sample", "--config", roots.config, "--input", roots.input, "--chunk_cache", "bypass"}
+			args = append(args, tt.flags...)
+			var stdout, stderr bytes.Buffer
+			code := RunWithOptions(args, &stdout, &stderr, newStateTestHarness().options())
+			if code != tt.wantCode || (tt.wantOutput != "" && !strings.Contains(stdout.String(), tt.wantOutput)) || (tt.wantError != "" && !strings.Contains(stderr.String(), tt.wantError)) {
+				t.Fatalf("code=%d stdout=%q stderr=%q", code, stdout.String(), stderr.String())
+			}
+		})
+	}
+}
+
 func TestRunValidFailuresClassifyAndReportDebug(t *testing.T) {
 	tests := []struct {
 		name      string