Implement console.trace() (#2780)

groupCollapsed alias to group, remove noTrailingNewline, move newline 
out of stringifyArgs, fix console.dir, add tests, and fix a repl log quirk.
For repl logging quirks, I believe we should not indent repl logging. If
we really want such indentation, we probably also want to indent "> "
prompts.

3 files changed, 81 insertions, 63 deletions

diff --git a/js/console.ts b/js/console.ts
index ed6040f1d..002be6e2f 100644
--- a/js/console.ts
+++ b/js/console.ts
@@ -11,7 +11,6 @@ type ConsoleOptions = Partial<{
   depth: number;
   colors: boolean;
   indentLevel: number;
-  collapsedAt: number | null;
 }>;
 
 // Default depth of logging nested objects
@@ -469,18 +468,13 @@ export function stringifyArgs(
     a++;
   }
 
-  const { collapsedAt, indentLevel } = options;
-  const isCollapsed =
-    collapsedAt != null && indentLevel != null && collapsedAt <= indentLevel;
-  if (!isCollapsed) {
-    if (indentLevel != null && indentLevel > 0) {
-      const groupIndent = " ".repeat(indentLevel);
-      if (str.indexOf("\n") !== -1) {
-        str = str.replace(/\n/g, `\n${groupIndent}`);
-      }
-      str = groupIndent + str;
+  const { indentLevel } = options;
+  if (indentLevel != null && indentLevel > 0) {
+    const groupIndent = " ".repeat(indentLevel);
+    if (str.indexOf("\n") !== -1) {
+      str = str.replace(/\n/g, `\n${groupIndent}`);
     }
-    str += "\n";
+    str = groupIndent + str;
   }
 
   return str;
@@ -494,13 +488,11 @@ export const isConsoleInstance = Symbol("isConsoleInstance");
 
 export class Console {
   indentLevel: number;
-  collapsedAt: number | null;
   [isConsoleInstance]: boolean = false;
 
   /** @internal */
   constructor(private printFunc: PrintFunc) {
     this.indentLevel = 0;
-    this.collapsedAt = null;
     this[isConsoleInstance] = true;
 
     // ref https://console.spec.whatwg.org/#console-namespace
@@ -516,9 +508,8 @@ export class Console {
   log = (...args: unknown[]): void => {
     this.printFunc(
       stringifyArgs(args, {
-        indentLevel: this.indentLevel,
-        collapsedAt: this.collapsedAt
-      }),
+        indentLevel: this.indentLevel
+      }) + "\n",
       false
     );
   };
@@ -530,16 +521,15 @@ export class Console {
 
   /** Writes the properties of the supplied `obj` to stdout */
   dir = (obj: unknown, options: ConsoleOptions = {}): void => {
-    this.log(stringifyArgs([obj], options));
+    this.printFunc(stringifyArgs([obj], options) + "\n", false);
   };
 
   /** Writes the arguments to stdout */
   warn = (...args: unknown[]): void => {
     this.printFunc(
       stringifyArgs(args, {
-        indentLevel: this.indentLevel,
-        collapsedAt: this.collapsedAt
-      }),
+        indentLevel: this.indentLevel
+      }) + "\n",
       true
     );
   };
@@ -732,21 +722,12 @@ export class Console {
     this.indentLevel += 2;
   };
 
-  groupCollapsed = (...label: unknown[]): void => {
-    if (this.collapsedAt == null) {
-      this.collapsedAt = this.indentLevel;
-    }
-    this.group(...label);
-  };
+  groupCollapsed = this.group;
 
   groupEnd = (): void => {
     if (this.indentLevel > 0) {
       this.indentLevel -= 2;
     }
-    if (this.collapsedAt != null && this.collapsedAt >= this.indentLevel) {
-      this.collapsedAt = null;
-      this.log(); // When the collapsed state ended, outputs a sinle new line.
-    }
   };
 
   clear = (): void => {
@@ -755,6 +736,17 @@ export class Console {
     clearScreenDown(stdout);
   };
 
+  trace = (...args: unknown[]): void => {
+    const message = stringifyArgs(args, { indentLevel: 0 });
+    const err = {
+      name: "Trace",
+      message
+    };
+    // @ts-ignore
+    Error.captureStackTrace(err, this.trace);
+    this.error((err as Error).stack);
+  };
+
   static [Symbol.hasInstance](instance: Console): boolean {
     return instance[isConsoleInstance];
   }
diff --git a/js/console_test.ts b/js/console_test.ts
index e7cc360bc..8070ee0f0 100644
--- a/js/console_test.ts
+++ b/js/console_test.ts
@@ -143,7 +143,7 @@ test(function consoleTestStringifyCircular(): void {
   assertEquals(stringify(JSON), "{}");
   assertEquals(
     stringify(console),
-    "{ printFunc, log, debug, info, dir, warn, error, assert, count, countReset, table, time, timeLog, timeEnd, group, groupCollapsed, groupEnd, clear, indentLevel, collapsedAt }"
+    "{ printFunc, log, debug, info, dir, warn, error, assert, count, countReset, table, time, timeLog, timeEnd, group, groupCollapsed, groupEnd, clear, trace, indentLevel }"
   );
   // test inspect is working the same
   assertEquals(inspect(nestedObj), nestedObjExpected);
@@ -155,16 +155,16 @@ test(function consoleTestStringifyWithDepth(): void {
   const nestedObj: any = { a: { b: { c: { d: { e: { f: 42 } } } } } };
   assertEquals(
     stringifyArgs([nestedObj], { depth: 3 }),
-    "{ a: { b: { c: [Object] } } }\n"
+    "{ a: { b: { c: [Object] } } }"
   );
   assertEquals(
     stringifyArgs([nestedObj], { depth: 4 }),
-    "{ a: { b: { c: { d: [Object] } } } }\n"
+    "{ a: { b: { c: { d: [Object] } } } }"
   );
-  assertEquals(stringifyArgs([nestedObj], { depth: 0 }), "[Object]\n");
+  assertEquals(stringifyArgs([nestedObj], { depth: 0 }), "[Object]");
   assertEquals(
     stringifyArgs([nestedObj], { depth: null }),
-    "{ a: { b: { c: { d: [Object] } } } }\n"
+    "{ a: { b: { c: { d: [Object] } } } }"
   );
   // test inspect is working the same way
   assertEquals(
@@ -378,15 +378,8 @@ test(function consoleGroup(): void {
       console.log("4");
       console.groupEnd();
       console.groupEnd();
-
-      console.groupCollapsed("5");
+      console.log("5");
       console.log("6");
-      console.group("7");
-      console.log("8");
-      console.groupEnd();
-      console.groupEnd();
-      console.log("9");
-      console.log("10");
 
       assertEquals(
         out.toString(),
@@ -394,9 +387,8 @@ test(function consoleGroup(): void {
   2
   3
     4
-5678
-9
-10
+5
+6
 `
       );
     }
@@ -417,16 +409,8 @@ test(function consoleGroupWarn(): void {
       console.groupEnd();
       console.warn("5");
 
-      console.groupCollapsed();
       console.warn("6");
-      console.group();
       console.warn("7");
-      console.groupEnd();
-      console.warn("8");
-      console.groupEnd();
-
-      console.warn("9");
-      console.warn("10");
       assertEquals(
         both.toString(),
         `1
@@ -434,9 +418,8 @@ test(function consoleGroupWarn(): void {
     3
   4
 5
-678
-9
-10
+6
+7
 `
       );
     }
@@ -652,3 +635,29 @@ test(function consoleLogShouldNotThrowError(): void {
     }
   );
 });
+
+// console.dir test
+test(function consoleDir(): void {
+  mockConsole(
+    (console, out): void => {
+      console.dir("DIR");
+      assertEquals(out.toString(), "DIR\n");
+    }
+  );
+  mockConsole(
+    (console, out): void => {
+      console.dir("DIR", { indentLevel: 2 });
+      assertEquals(out.toString(), "  DIR\n");
+    }
+  );
+});
+
+// console.trace test
+test(function consoleTrace(): void {
+  mockConsole(
+    (console, _out, err): void => {
+      console.trace("%s", "custom message");
+      assert(err.toString().includes("Trace: custom message"));
+    }
+  );
+});
diff --git a/js/repl.ts b/js/repl.ts
index be162cb7e..daf4fd154 100644
--- a/js/repl.ts
+++ b/js/repl.ts
@@ -8,6 +8,23 @@ import { exit } from "./os";
 import { window } from "./window";
 import { core } from "./core";
 import { formatError } from "./format_error";
+import { stringifyArgs } from "./console";
+
+/**
+ * REPL logging.
+ * In favor of console.log to avoid unwanted indentation
+ */
+function replLog(...args: unknown[]): void {
+  core.print(stringifyArgs(args) + "\n");
+}
+
+/**
+ * REPL logging for errors.
+ * In favor of console.error to avoid unwanted indentation
+ */
+function replError(...args: unknown[]): void {
+  core.print(stringifyArgs(args) + "\n", true);
+}
 
 const helpMsg = [
   "exit    Exit the REPL",
@@ -86,7 +103,7 @@ function isRecoverableError(e: Error): boolean {
 function evaluate(code: string): boolean {
   const [result, errInfo] = core.evalContext(code);
   if (!errInfo) {
-    console.log(result);
+    replLog(result);
   } else if (errInfo.isCompileError && isRecoverableError(errInfo.thrown)) {
     // Recoverable compiler error
     return false; // don't consume code.
@@ -95,9 +112,9 @@ function evaluate(code: string): boolean {
       const formattedError = formatError(
         core.errorToJSON(errInfo.thrown as Error)
       );
-      console.error(formattedError);
+      replError(formattedError);
     } else {
-      console.error("Thrown:", errInfo.thrown);
+      replError("Thrown:", errInfo.thrown);
     }
   }
   return true;
@@ -135,7 +152,7 @@ export async function replLoop(): Promise<void> {
           // e.g. this happens when we have deno.close(3).
           // We want to display the problem.
           const formattedError = formatError(core.errorToJSON(err));
-          console.error(formattedError);
+          replError(formattedError);
         }
         // Quit REPL anyways.
         quitRepl(1);
@@ -157,7 +174,7 @@ export async function replLoop(): Promise<void> {
           // e.g. this happens when we have deno.close(3).
           // We want to display the problem.
           const formattedError = formatError(core.errorToJSON(err));
-          console.error(formattedError);
+          replError(formattedError);
           quitRepl(1);
         }
       }