svelte-istanbul-reproduction

Svelte Istanbul Reproduction

Demonstrating Svelte's sourcemap issues with IstanbulJS

Examples - Working sourcemaps | Examples - Broken sourcemaps

Reproduction / debugging setup for sveltejs/svelte#7824.

git clone https://github.com/AriPerkkio/svelte-istanbul-reproduction.git
cd svelte-istanbul-reproduction
pnpm i
pnpm start
npx [email protected] ./coverage

Check ./generated/ for results:

/x/svelte-istanbul-reproduction
├── debug-svelte-sourcemaps.mjs
└── generated
   ├── coverage-final.json
   ├── coverage-pre.json
   ├── instrumented.js
   ├── instrumented.js.map
   ├── instrumented.mappings.json
   ├── instrumented.remapped.md
   ├── transpiled.js
   ├── transpiled.js.map
   ├── transpiled.mappings.json
   └── transpiled.remapped.md

Remove following from package.json if local Svelte compiler is not present:

-  "pnpm": {
-    "overrides": {
-      "svelte": "link:../svelte"
-    }
-  }

Examples

Working sourcemaps

Line 16 described below.

Decoded mappings of transpiled.js.map

75 | [[26, 0, 15, 7], [29, 0, 15, 12], [33, 0, 15, 13], [39, 0, 15, 19], [44, 0, 15, 24], [45, 0, 15, 25]]

Mapping pairs:

  • #1 [26, 0, 15, 7], [29, 0, 15, 12]
  • #2 [33, 0, 15, 13], [39, 0, 15, 19]
  • #3 [44, 0, 15, 24], [45, 0, 15, 25]

transpiled.js

75                | let if_block = /*users*/ ctx[0].length === 0 && create_if_block(ctx);
Mapping pair #1   |                          ^^^    |    |     |
Mapping pair #2   |                                 ^^^^^^     |
Mapping pair #3   |                                            ^

Map to repro.svelte

16                |  {#if users.length === 0}
Mapping pair #1   |       ^^^^^ |    |     |
Mapping pair #2   |             ^^^^^^     |
Mapping pair #3   |                        ^

Decoded mappings of instrumented.js.map

1963 |  [[54, 0, 15, 7], [86, 0, 15, 12], [90, 0, 15, 13, 3], [96, 0, 15, 19], [101, 0, 15, 24], [102, 0, 15, 25]]
1964 |  [[2, 0, 15, 25]]

Mapping pairs:

  • #1 [54, 0, 15, 7], [86, 0, 15, 12]
  • #2 [90, 0, 15, 13, 3], [96, 0, 15, 19]
  • #3 [101, 0, 15, 24], [102, 0, 15, 25]
  • #4 [2, 0, 15, 25]

instrumented.js

1963                |  let if_block = ( /*users*/cov_208gup579f().s[24]++, (cov_208gup579f().b[4][0]++, ctx[0].length === 0) && (cov_208gup579f().b[4][1]++, create_if_block(ctx)));
Mapping pair #1     |                                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^    |    |     |
Mapping pair #2     |                                                                                          ^^^^^^     |
Mapping pair #3     |                                                                                                     ^
1964                |  cov_208gup579f().s[25]++;
Mapping pair #4     |  ^

Map to repro.svelte

16                  |  {#if users.length === 0}
Mapping pair #1     |       ^^^^^ |    |     |
Mapping pair #2     |             ^^^^^^     |
Mapping pair #3     |                        ^
Mapping pair #4     |                        ^

Coverage map before remapping

"branchMap": {
  "4": {
    "type": "binary-expr",
    "loc": {
      "start": { "line": 75, "column": 26 },
      "end": { "line": 75, "column": 69 }
    },
    "locations": [
      {
        "start": { "line": 75, "column": 26 },
        "end": { "line": 75, "column": 45 }
      },
      {
        "start": { "line": 75, "column": 49 },
        "end": { "line": 75, "column": 69 }
      }
    ],
    "line": 75
  }
}
75                          | let if_block = /*users*/ ctx[0].length === 0 && create_if_block(ctx);
branchMap["4"].locations[1] |                          ^^^^^^^^^^^^^^^^^^^    |                   |
branchMap["4"].locations[2] |                                                 ^^^^^^^^^^^^^^^^^^^^^

Coverage map after remapping

"branchMap": {
  "2": {
    "type": "binary-expr",
    "loc": {
      "start": { "line": 16, "column": 7 },
      "end": { "line": 16, "column": null }
    },
    "locations": [
      {
      "start": { "line": 16, "column": 7 },
      "end": { "line": 16, "column": 25 }
      },
      {
      "start": { "line": 16, "column": 25 },
      "end": { "line": 16, "column": null }
      }
    ]
  }
}
16           |  {#if users.length === 0}
locations[1] |       ^^^^^^^^^^^^^^^^^^
locations[2] |                        ^// Implicit else

Broken sourcemaps

Line 13 described below.

Decoded mappings of transpiled.js.map

26 | [[24, 0, 12, 9], [27, 0, 12, 13]]
35 | [[3, 0, 12, 4], [9, 0, 12, 19]]
39 | [[62, 0, 12, 9], [65, 0, 12, 13]]

Mapping pairs:

  • #1 [24, 0, 12, 9], [27, 0, 12, 13]
  • #2 [3, 0, 12, 4], [9, 0, 12, 19]
  • #3 [62, 0, 12, 9], [65, 0, 12, 13]

transpiled.js

26                |  let t_value = /*user*/ ctx[1] + "";
Mapping pair #1   |                         ^^^
35                |   insert(target, li, anchor);
Mapping pair #2   |   ^^^^^^
39                |   if (dirty & /*users*/ 1 && t_value !== (t_value = /*user*/ ctx[1] + "")) set_data(t, t_value);
Mapping pair #3   |                                                              ^^^

Map to repro.svelte

13                |    <li>{user}</li>
Mapping pair #1   |    |    ^^^^     |
Mapping pair #2   |    ^^^^^^^^^^^^^^^
Mapping pair #3   |         ^^^^

Decoded mappings of instrumented.js.map

1878 | [[51, 0, 12, 9, 0],[54, 0, 12, 13]]
1892 | [[6, 0, 12, 4, 1],[12, 0, 12, 19]]
1893 | [[6, 0, 12, 19]]
1899 | [[122, 0, 12, 9, 0],[125, 0, 12, 13]]
1900 | [[8, 0, 12, 13]]
1901 | [[8, 0, 12, 13]]
1902 | [[8, 0, 12, 13, 2]]
1903 | [[6, 0, 12, 13]]
1904 | [[8, 0, 12, 13]]
1905 | [[6, 0, 12, 13]]

Mapping pairs:

  • #1 [51, 0, 12, 9, 0],[54, 0, 12, 13]
  • #2 [6, 0, 12, 4, 1],[12, 0, 12, 19]
  • #3 [6, 0, 12, 19]
  • #4 [122, 0, 12, 9, 0],[125, 0, 12, 13]
  • #5 [8, 0, 12, 13]
  • #6 [8, 0, 12, 13]
  • #7 [8, 0, 12, 13, 2]
  • #8 [6, 0, 12, 13]
  • #9 [8, 0, 12, 13]
  • #10 [6, 0, 12, 13]

instrumented.js

1878                |  let t_value = ( /*user*/cov_208gup579f().s[3]++, ctx[1] + "");
Mapping pair #1     |                                                   ^^^
1892                |      insert(target, li, anchor);
Mapping pair #2     |      ^^^^^^
1893                |      cov_208gup579f().s[8]++;
Mapping pair #3     |      ^
1899                |      if ((cov_208gup579f().b[1][0]++, dirty & /*users*/1) && (cov_208gup579f().b[1][1]++, t_value !== (t_value = /*user*/ctx[1] + ""))) {
Mapping pair #4     |                                                                                                                          ^^^
1900                |        cov_208gup579f().b[0][0]++;
Mapping pair #5     |        ^
1901                |        cov_208gup579f().s[10]++;
Mapping pair #6     |        ^
1902                |        set_data(t, t_value);
Mapping pair #7     |        ^
1903                |      } else {
Mapping pair #8     |      ^
1904                |        cov_208gup579f().b[0][1]++;
Mapping pair #9     |        ^
1905                |      }
Mapping pair #10    |      ^

Map to repro.svelte

13                  |    <li>{user}</li>
Mapping pair #1     |    |    ^^^^     |
Mapping pair #2     |    ^^^^^^^^^^^^^^^
Mapping pair #3     |         |  |     ^
Mapping pair #4     |         ^^^^
Mapping pair #5     |            ^
Mapping pair #6     |            ^
Mapping pair #7     |            ^
Mapping pair #8     |            ^
Mapping pair #9     |            ^
Mapping pair #10    |            ^

Coverage map before remapping

"statementMap": {
  "3": {
    "start": { "line": 26, "column": 24 },
    "end": { "line": 26, "column": 35 }
  },
  "7": {
    "start": { "line": 35, "column": 3 },
    "end": { "line": 35, "column": 30 }
  },
  "9": {
    "start": { "line": 39, "column": 3 },
    "end": { "line": 39, "column": 97 }
  },
  "10": {
    "start": { "line": 39, "column": 76 },
    "end": { "line": 39, "column": 97 }
  }
},
"branchMap": {
  "0": {
    "loc": {
      "start": { "line": 39, "column": 3 },
      "end": { "line": 39, "column": 97 }
    },
    "type": "if",
    "locations": [
      {
        "start": { "line": 39, "column": 3 },
        "end": { "line": 39, "column": 97 }
      },
      { "start": {}, "end": {} } // Implicit else
    ],
    "line": 39
  },
  "1": {
    "loc": {
      "start": { "line": 39, "column": 7 },
      "end": { "line": 39, "column": 74 }
    },
    "type": "binary-expr",
    "locations": [
      {
        "start": { "line": 39, "column": 7 },
        "end": { "line": 39, "column": 26 }
      },
      {
        "start": { "line": 39, "column": 30 },
        "end": { "line": 39, "column": 74 }
      }
    ],
    "line": 39
  }
}
26                          |  let t_value = /*user*/ ctx[1] + "";
statementMap["3"]           |                         ^^^^^^^^^^^
35                          |   insert(target, li, anchor);
statementMap["7"]           |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
39                          |   if (dirty & /*users*/ 1 && t_value !== (t_value = /*user*/ ctx[1] + "")) set_data(t, t_value);
statementMap["9"]           |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
statementMap["10"]          |                                                                            ^^^^^^^^^^^^^^^^^^^^^
branchMap["0"].locations[0] |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
branchMap["1"].locations[0] |       ^^^^^^^^^^^^^^^^^^^                                                
branchMap["1"].locations[1] |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Coverage map after remapping

"statementMap": {
  "0": {
    "start": { "line": 13, "column": 9 },
    "end": { "line": 13, "column": 19 }
  },
  "1": {
    "start": { "line": 13, "column": 4 },
    "end": { "line": 13, "column": null }
  },
  "2": {
    "start": { "line": 13, "column": 13 },
    "end": { "line": 13, "column": 19 }
  },
  ...
},
"branchMap": {
  "0": {
    "loc": { "start": { "line": 13, "column": 9 }, "end": { "line": 13, "column": 19 } },
    "type": "if",
    "locations": [
      { 
        "start": { "line": 13, "column": 9 },
        "end": { "line": 13, "column": 19 }
      }
    ]
  },
  "1": {
    "loc": { "start": { "line": 13, "column": 9 }, "end": { "line": 13, "column": 19 } },
    "type": "binary-expr",
    "locations": [
      {
        "start": { "line": 13, "column": 9 },
        "end": { "line": 13, "column": 13 }
      },
      {
        "start": { "line": 13, "column": 9 },
        "end": { "line": 13, "column": 19 }
      }
    ]
  },
  ...
}
13                          |    <li>{user}</li>
statementMap["0"]           |         ^^^^^^^^^^
statementMap["1"]           |    ^
statementMap["2"]           |             ^^^^^^
branchMap["0"].locations[0] |         ^^^^^^^^^^
branchMap["1"].locations[0] |         ^^^^
branchMap["1"].locations[1] |         ^^^^^^^^^^

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