R Under development (unstable) (2026-01-26 r89334 ucrt) -- "Unsuffered Consequences"
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> library(testthat)
> library(igraph)

Attaching package: 'igraph'

The following object is masked from 'package:testthat':

    compare

The following objects are masked from 'package:stats':

    decompose, spectrum

The following object is masked from 'package:base':

    union

> 
> test_check("igraph")
Starting 2 test processes.
Saving _problems/test-other-168.R
Saving _problems/test-versions-35.R
Saving _problems/test-versions-50.R
Saving _problems/test-versions-65.R
[ FAIL 4 | WARN 0 | SKIP 112 | PASS 5775 ]

══ Skipped tests (112) ═════════════════════════════════════════════════════════
• On CRAN (108): 'test-aaa-auto.R:2:1', 'test-adjacency.R:610:1',
  'test-adjacency.R:639:1', 'test-adjacency.R:788:1',
  'test-attributes.R:437:1', 'test-attributes.R:466:1',
  'test-attributes.R:473:1', 'test-centrality.R:32:1',
  'test-centrality.R:88:1', 'test-centrality.R:145:3',
  'test-centrality.R:819:1', 'test-centrality.R:830:1',
  'test-community.R:378:1', 'test-conversion.R:47:1', 'test-conversion.R:54:1',
  'test-conversion.R:143:1', 'test-conversion.R:198:1',
  'test-conversion.R:566:1', 'test-conversion.R:680:1', 'test-flow.R:98:1',
  'test-flow.R:143:1', 'test-flow.R:180:1', 'test-flow.R:193:1',
  'test-flow.R:213:1', 'test-flow.R:226:1', 'test-flow.R:250:1',
  'test-flow.R:292:1', 'test-fit.R:30:1', 'test-foreign.R:24:1',
  'test-foreign.R:33:1', 'test-foreign.R:42:1', 'test-foreign.R:51:1',
  'test-foreign.R:55:1', 'test-foreign.R:62:3', 'test-hrg.R:10:1',
  'test-hrg.R:20:1', 'test-hrg.R:27:1', 'test-incidence.R:1:1',
  'test-incidence.R:19:1', 'test-incidence.R:112:1', 'test-incidence.R:130:1',
  'test-incidence.R:214:1', 'test-incidence.R:230:1', 'test-games.R:66:1',
  'test-games.R:90:1', 'test-interface.R:181:1', 'test-interface.R:202:1',
  'test-iterators.R:327:1', 'test-iterators.R:347:1', 'test-iterators.R:368:1',
  'test-iterators.R:444:1', 'test-layout.R:17:1', 'test-layout.R:158:3',
  'test-layout.R:213:1', 'test-layout.R:335:1',
  'test-minimum.spanning.tree.R:35:1', 'test-make.R:43:1', 'test-make.R:69:1',
  'test-make.R:78:1', 'test-make.R:86:1', 'test-make.R:96:1',
  'test-make.R:104:1', 'test-make.R:269:1', 'test-other.R:30:1',
  'test-other.R:39:3', 'test-other.R:52:1', 'test-other.R:161:1',
  'test-palette.R:192:1', 'test-palette.R:225:1', 'test-par.R:1:1',
  'test-par.R:11:1', 'test-paths.R:18:1', 'test-paths.R:42:1',
  'test-plot.R:1:1', 'test-plot.R:26:1', 'test-plot.R:51:1',
  'test-plot.R:89:1', 'test-plot.R:119:1', 'test-plot.R:142:1',
  'test-plot.R:150:1', 'test-plot.R:172:1', 'test-plot.R:189:1',
  'test-plot.R:214:1', 'test-plot.R:237:1', 'test-plot.shapes.R:129:1',
  'test-plot.shapes.R:159:1', 'test-plot.shapes.R:181:1',
  'test-plot.shapes.R:229:1', 'test-print.R:74:1', 'test-print.R:84:1',
  'test-print.R:101:1', 'test-print.R:117:1', 'test-print.R:132:1',
  'test-operators.R:216:1', 'test-structural-properties.R:20:1',
  'test-structural-properties.R:187:1', 'test-structural-properties.R:207:1',
  'test-structural-properties.R:754:1', 'test-trees.R:218:1',
  'test-utils-assert-args.R:1:1', 'test-utils-assert-args.R:9:1',
  'test-versions.R:8:1', 'test-versions.R:14:1', 'test-versions.R:24:1',
  'test-versions.R:39:1', 'test-versions.R:54:1', 'test-versions.R:69:1',
  'test-versions.R:94:1'
• nested igraph call handling not implemented yet (1):
  'test-structural-properties.R:174:3'
• {graph} is not installed (2): 'test-conversion.R:527:3',
  'test-conversion.R:555:3'
• {pcalg} is not installed (1): 'test-adjacency.R:20:3'

══ Failed tests ════════════════════════════════════════════════════════════════
── Error ('test-other.R:168:3'): VS/ES work with old data type ─────────────────
Error in `upgrade_graph(karate)`: igraph object is too old to upgrade.
Backtrace:
    ▆
 1. └─igraph::upgrade_graph(karate) at test-other.R:168:3
── Error ('test-versions.R:35:3'): we can upgrade from 0.2 to 1.5.0, explicitly ──
Error in `upgrade_graph(g)`: igraph object is too old to upgrade.
Backtrace:
    ▆
 1. └─igraph::upgrade_graph(g) at test-versions.R:35:3
── Error ('test-versions.R:50:3'): we can upgrade from 0.5 to 1.5.0, explicitly ──
Error in `upgrade_graph(g)`: igraph object is too old to upgrade.
Backtrace:
    ▆
 1. └─igraph::upgrade_graph(g) at test-versions.R:50:3
── Error ('test-versions.R:65:3'): we can upgrade from 0.6 to 1.5.0, explicitly ──
Error in `upgrade_graph(g)`: igraph object is too old to upgrade.
Backtrace:
    ▆
 1. └─igraph::upgrade_graph(g) at test-versions.R:65:3

[ FAIL 4 | WARN 0 | SKIP 112 | PASS 5775 ]
Error:
! Test failures.
Execution halted