Add --example flag and improve diff formatting

src/cli/index.ts

@@ -54,7 +54,28 @@ program
   .option("--timeout <dur>", "Per-command timeout", "10s")
   .option("-v, --verbose", "Print each command as it runs")
   .option("--parallel", "Run files in parallel")
+  .option("--example", "Print an example .shout file and exit")
   .action(async (fileArgs: string[], opts) => {
+    if (opts.example) {
+      console.log(`# Example .shout file
+$ echo hello
+hello
+
+$ echo "one"; echo "two"; echo "three"
+one
+...
+three
+
+$ cat nonexistent
+cat: nonexistent: ...
+[1]
+
+$ exit 0
+[0]`)
+      process.exit(0)
+    }
+
+
     const timeoutMs = parseDuration(opts.timeout)
     const paths = fileArgs.length > 0 ? fileArgs : ["."]
     const files = await findShoutFiles(paths)

src/format.ts

@@ -70,20 +70,20 @@ export function formatFailure(test: TestResult): string {
     lines.push("")
     lines.push(`  ${ansis.dim("$")} ${failure.result.command.command}`)
 
-    for (const dl of failure.diffLines) {
-      switch (dl.kind) {
-        case "equal":
-          lines.push(`  ${dl.text}`)
-          break
-        case "expected":
-          lines.push(ansis.red(`  - ${dl.text}`))
-          break
-        case "actual":
-          lines.push(ansis.green(`  + ${dl.text}`))
-          break
-        case "context":
-          lines.push(ansis.dim(`  ${dl.text}`))
-          break
+    if (failure.diffLines.length > 0) {
+      lines.push(ansis.red("  expected:"))
+      for (const dl of failure.diffLines) {
+        if (dl.kind === "expected" || dl.kind === "equal" || dl.kind === "context") {
+          const prefix = dl.kind === "expected" ? ansis.red("  > ") : "    "
+          lines.push(`${prefix}${dl.kind === "context" ? ansis.dim(dl.text) : dl.text}`)
+        }
+      }
+      lines.push(ansis.green("  actual:"))
+      for (const dl of failure.diffLines) {
+        if (dl.kind === "actual" || dl.kind === "equal" || dl.kind === "context") {
+          const prefix = dl.kind === "actual" ? ansis.green("  > ") : "    "
+          lines.push(`${prefix}${dl.kind === "context" ? ansis.dim(dl.text) : dl.text}`)
+        }
       }
     }
 
@@ -91,9 +91,9 @@ export function formatFailure(test: TestResult): string {
       const expected = failure.result.command.exitCode ?? 0
       const actual = failure.result.exitCode
       lines.push(
-        ansis.red(`  - exit code: ${expected === "*" ? "non-zero" : expected}`),
+        ansis.red(`  expected exit code: ${expected === "*" ? "non-zero" : expected}`),
       )
-      lines.push(ansis.green(`  + exit code: ${actual}`))
+      lines.push(ansis.green(`  actual exit code: ${actual}`))
     }
   }